Transition metal carbene complexes containing a cationic substituent as catalysts of olefin metathesis reactions

ABSTRACT

Organometallic complexes suitable as olefin metathesis catalysts are provided. The complexes are Group 8 transition metal carbenes bearing a cationic substituent and having the general structure (I) 
                         
wherein M is a Group 8 transition metal, L 1  and L 2  are neutral electron donor ligands, X 1  and X 2  are anionic ligands, m is zero or 1, n is zero or 1, and R 1 , W, Y, and Z are as defined herein. Methods for synthesizing the complexes are also provided, as are methods for using the complexes as olefin metathesis catalysts.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e)(1) toProvisional U.S. Patent Application Ser. No. 60/578,200, filed Jun. 9,2004, the disclosure of which is incorporated by reference herein.

TECHNICAL FIELD

This invention relates generally to olefin metathesis catalysts, andmore particularly pertains to new Group 8 transition metal complexesthat are useful as olefin metathesis catalysts. The invention hasutility in the fields of catalysis, organic synthesis, andorganometallic chemistry.

BACKGROUND OF THE INVENTION

Olefin metathesis catalysis is a powerful technology, which in recentyears has received tremendous attention as a versatile method for theformation of carbon-carbon bonds and has numerous applications inorganic synthesis and polymer chemistry (R. H. Grubbs, Handbook ofMetathesis, Vol. 2 and 3; Wiley VCH, Weinheim, 2003). The family ofolefin metathesis reactions includes ring-closing metathesis (RCM),cross metathesis (CM or XMET), ring-opening metathesis polymerization(ROMP), and acyclic diene metathesis polymerization (ADMET). The successof olefin metathesis stems from the development of several well-definedtransition metal complexes, such as the Schrock molybdenum catalysts andthe Grubbs ruthenium and osmium catalysts (see, e.g., Schrock (1999)Tetrahedron 55, 8141-8153; Schrock (1990) Acc. Chem. Res. 23, 158-165;Grubbs et al. (1998) Tetrahedron 54, 4413-4450; Tmka et al. (2001) Acc.Chem. Res. 34, 18-29; Grubbs, Handbook of Metathesis, Vol. 1; Wiley VCH,Weinheim, 2003). Following the discovery of these complexes, asignificant amount of olefin metathesis research has focused on tuningthe ruthenium and osmium carbene catalysts in order to increase theiractivity, selectivity, and/or stability. The most common strategy hasinvolved the replacement of mono-dentate ligands with other mono-dentateligands to provide the catalytic complexes with new and usefulproperties.

The original breakthrough ruthenium catalysts were primarilybisphosphine complexes of the general formula (PR₃)₂(X)₂M═CHR′ wherein Mis ruthenium (Ru) or osmium (Os), X represents a halogen (e.g., Cl, Br,or I), R represents an alkyl, cycloalkyl, or aryl group (e.g., butyl,cyclohexyl, or phenyl), and R′ represents an alkyl, alkenyl, or arylgroup (e.g., methyl, CH═C(CH₃)₂, phenyl, etc.) (see Nguyen et al. (1992)J. Am. Chem. Soc. 1992, 114, 3974-3975; Schwab et al. (1995) Angew.Chem., Int. Ed. 34, 2039-2041; Schwab et al. (1996) J. Am. Chem. Soc.118, 100-110). Examples of these types of catalysts are described inU.S. Pat. Nos. 5,312,940, 5,969,170 and 6,111,121 to Grubbs et al. Whilesuch complexes are capable of catalyzing a considerable number of olefinmetathesis transformations, these bisphosphine complexes can exhibitlower activity than desired and, under certain conditions, can havelimited lifetimes.

More recent developments in the field have led to increased activity andstability by replacing one of the phosphine ligands with a bulkyN-heterocyclic carbene (NHC) ligand (Scholl et al. (1999) OrganicLetters 1, 953-956) to give complexes of the general formula(L)(PR₃)(X)₂Ru═CHR′, wherein L represents an NHC ligand such as1,3-dimesitylimidazole-2-ylidene (IMes) and1,3-dimesityl-4,5-dihydroimidazol-2-ylidene (sIMes), X represents ahalogen (e.g., Cl, Br, or I), R represents an alkyl, cycloalkyl, or arylgroup (e.g., butyl, cyclohexyl, or phenyl), and R′ represents an alkyl,alkenyl, or aryl group (e.g., methyl, CH═C(CH₃)₂, phenyl, etc.).Representative structures include complex A (ibid.), complex B (Garberet al. (2000) J. Am. Chem. Soc. 122, 8168-8179), and complex C (Sanfordet al. (2001) Organometallics 20, 5314-5318; Love et al. (2002) Angew.Chem., Int. Ed. 41, 4035-4037):

Unlike prior bisphosphine complexes, the various imidazolylidinecatalysts effect the efficient formation of trisubstituted andtetrasubstituted olefins through catalytic metathesis. Examples of thesetypes of catalysts are described in PCT publications WO 99/51344 and WO00/71554. Further examples of the synthesis and reactivity of some ofthese active ruthenium complexes are reported by Fürstner et al. (2001)Chem. Eur. J. 7, No. 15, 3236-3253; Blackwell et al. (2000) J. Am. Chem.Soc. 122, 58-71; Chatterjee et al. (2000) J. Am. Chem. Soc. 122,3783-3784; Chatterjee etal. (2000) Angew. Chem. Int. Ed. 41, 3171-3174;Chatterjee et al. (2003) J. Am. Chem. Soc. 125, 11360-11370. Furthertuning of these catalysts led to even higher activity by using bulkierimidazolylidine ligands such as1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidenes (Dinger etal. (2002) Adv. Synth. Catal. 344, 671-677) or electron deficientphosphine ligands such as fluorinated aryl phosphines (Love et al.(2003) J. Am. Chem. Soc. 125, 10103-10109).

Another example of ligand substitution that has led to enhanced catalystactivity is the replacement of the phosphine ligand in the(L)(PR₃)(X)₂M═CHR′ complexes with one or two pyridine-type ligands togive compounds of the general formula (L)(L′)_(n)(X)₂M═CHR′ wherein n=1or 2, L represents an imidazolylidine ligand, L′ represents a pyridine(Py) or substituted pyridine ligand, X represents a halogen (e.g., Cl,Br, or I), and R¹ represents an alkyl, alkenyl, or aryl group (e.g.,methyl, CH═C(CH₃)₂, phenyl, etc.). These pyridine complexes areextremely fast-initiating and catalyze living ring-opening metathesispolymerizations (Choi et al. (2003) Chem. Int. Ed. 42, 1743-1746) aswell as highly challenging processes such as olefin cross metathesiswith acrylonitrile (Love et al. (2002) Angew. Chem. Int. Ed. 41,4035-4037).

Yet another example of mono-dentate ligand substitution is thereplacement of the halogen ligands with aryl-oxo ligands, which in oneexample has led to a catalyst with enhanced activity:(L)(L′)_(n)(RO)₂Ru═CHR′ wherein n=1, L represents an imidazolylidineligand, L′ represents a pyridine ligand, R represents a fluorinated arylgroup, and R′ represents an alkyl, alkenyl, or aryl group (Conrad et al.(2003) Organometallics 22, 3634-3636).

A different strategy to tune olefin metathesis catalysts involveslinking two of the ligands that are attached to the metal center. Ofparticular interest are the chelating carbene species reported byHoveyda and others (Gaber et al. (2000) J. Am. Chem. Soc. 122,8168-8179; Kingsbury et al. (1999) J. Am. Chem. Soc. 121, 791-799;Harrity et al. (1997) J. Am. Chem. Soc. 119, 1488-1489; Harrity et al.(1998) J. Am. Chem. Soc. 120, 2343-2351). These catalysts areexceptionally stable and can be purified by column chromatography inair.

Fewer efforts to differentiate catalyst performance and regulate olefinmetathesis reactions have focused on the development of chargedruthenium metal complexes. Several groups have demonstrated cationiccompounds of the general type [(L)(L′)(X)Ru═(C)_(n)═CRR′]⁺ (L and L′ areany of a variety of neutral electron donors, X is typically halide, andn=0,1,2. . .). In U.S. Pat. No. 6,590,048, Fürstner teaches the use ofcationic vinylidene, allylidene and higher cumulene complexes for avariety of olefin metathesis reactions. In U.S. Pat. No. 6,500,975,Schwab and coworkers describe the use of cationic ruthenium alkylidynecomplexes and their use in the metathesis of electron poor olefins. InU.S. Pat. No. 6,225,488, Mukerjee et al. teach the use of cationic(bisallyl) vinylidene complexes of ruthenium or osmium for thering-opening metathesis polymerization of norbornene derivatives. Othercationic Group 8 metathesis catalysts have been described by Jung et al.(2001) Organometallics 20:2121; Cadiemo et al. (2001) Organometallics200:3175; De Clereq et al. (2002) Macromolecules 35:8943; Bassetti etal. (2003) 22:4459; Prühs et al. (2004) Organometallics 23:280; andVolland et al. (2004) Organometallics 23:800. These are typicallyderived from abstraction of an anionic ligand from the coordinationsphere of a neutral metal precursor. Alternatively, a cationic ligand ina neutral complex may be replaced by a neutral ligand resulting incationic metal complexes. Distinct from the above-described complexes,Audic et al. (2003) J. Am. Chem. Soc. 125:9248 makes use of olefin crossmetathesis to link an imidazolium salt to the carbene moiety of a Grubbsor a Grubbs-Hoveyda catalyst precursor. The immediate coordinationsphere of the resulting complexes remains intentionally unchanged, butthe distal imidazolium salt confers solubility to the catalyst precursorin certain ionic liquids . These efforts were directed to thedevelopment of ionic liquid “supported” catalysts to facilitate catalystrecycle.

As will be discussed in further detail infra, the root of the loweractivities of the some of the Grubbs catalysts, which may be genericallydenoted as X₂(L)(L′)Ru═C(H)R, lies in their mode of initiation and theaccessibility of the reactive species, the 14-electron alkylideneX₂(L)Ru═C(H)R formed upon reversible dissociation of L′. Most of theimprovements to the Grubbs “first generation” catalysts, e.g.,Cl₂(PCy₃)₂Ru═C(H)Ph (Cy=cyclohexyl), are modifications that eitherencourage loss of L′ (Love et al. (2003) J. Am. Chem. Soc. 125:10103) orreduce the tendency of Cl₂(L)Ru═C(H)R to re-capture the liberated L′(Sanford et al. (2001) J. Am. Chem. Soc. 123:6543) which competes withthe olefin substrate for the unsaturated metal center in Cl₂(L)Ru═C(H)R.Alternatively, Hoveyda had developed a series of catalysts in which L′is a loosely chelating group associated with the carbene ligand that isremoved upon the first metathesis event. See Kingsbury et al. (1999) J.Am. Chem. Soc. 121:791; Hoveyda (1999) J. Am. Chem. Soc. 121:791; andGarber et al. (2000) J. Am. Chem. Soc. 122:8168.

Despite these advances there remains a need for olefin metathesiscatalysts that are highly active as well as stable to air and moisture,thermally stable, and tolerant of functional groups on the olefinsubstrates. Ideal catalysts would also be “tunable” with regard toactivity, including initiation time and substrate conversion rate.

SUMMARY OF THE INVENTION

The invention is addressed to the aforementioned need in the art, andprovides new organometallic complexes useful as catalysts of olefinmetathesis reactions. Relative to known olefin metathesis catalysts, thenovel catalysts dramatically shorten the latency period of themetathesis reaction, significantly increase the rate at which thereaction occurs, and substantially shorten the time to reactioncompletion. As such, the complexes of the invention are highly activemetathesis catalysts.

In one embodiment, an organometallic complex useful as an olefinmetathesis catalyst is provided, the complex having the structure offormula (I)

wherein:

M is a Group 8 transition metal;

L¹ and L² are neutral electron donor ligands;

X¹ and X² are anionic ligands;

R¹ is hydrogen, C₁-C₁₂ hydrocarbyl, or substituted C₁-C₁₂ hydrocarbyl;

W is an optionally substituted and/or heteroatom-containing C₁-C₂₀hydrocarbylene linkage;

Y is a positively charged Group 15 or Group 16 element substituted withhydrogen, C₁-C₁₂ hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl;heteroatom-containing C₁-C₁₂ hydrocarbyl, or substitutedheteroatom-containing hydrocarbyl;

Z⁻ is a negatively charged counterion;

m is zero or 1; and

n is zero or 1;

wherein any two or more of L¹, L², X¹, X², R¹, W, and Y can be takentogether to form a cyclic group.

Exemplary catalysts are those wherein m and n are both zero.

In another embodiment, methods are provided for synthesizing theorganometallic complexes of the invention. One such method involvessynthesis of an organometallic complex having the structure of formula(XI)

wherein M is a Group 8 transition metal, L¹ is a neutral electron donorligand, X¹ and X² are anionic ligands, R¹ is hydrogen, C₁-C₁₂hydrocarbyl, or substituted C₁-C₁₂ hydrocarbyl, Y is a positivelycharged Group 15 or Group 16 element substituted with hydrogen, C₁-C₁₂hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl, heteroatom-containingC₁-C₁₂ hydrocarbyl, or substituted heteroatom-containing hydrocarbyl,and Z⁻ is a negatively charged ion, the method comprising contacting aGroup 8 transition metal carbide having the structure (XIII)

with an ionic reagent of the formula [R¹]⁺[Z]⁻. The [R¹]⁺ moiety in theionic reagent is typically hydrogen, and may be associated with a polarsolvent (as in [H(Et₂O)₂][B(C₆F₅)₄]⁻, also referred to as “Jutzi'sacid”; see Jutzi et al. (2000) Organometallics 19:1442).

The invention also provides a method for synthesizing an organometalliccomplex having the structure of formula (II)

wherein L¹, X¹, X², R¹, and Y are as defined previously, with Ypreferably being a C₁-C₁₂ hydrocarbyl-substituted, positively chargedGroup 15 or Group 16 element, and Z⁻ is of the formula B(R¹⁵)₄ ⁻ whereR¹⁵ is fluoro, aryl, or perfluorinated aryl, the method comprising:

(a) contacting (i) a ruthenium complex having the structure (XIV)

where R¹⁶ is C₁-C₂₀ hydrocarbyl, with (ii) a reagent effective toconvert the ruthenium complex to the ruthenium carbide (XV)

and (b) contacting the ruthenium carbide with a protonating reagent ofthe formula [H(OR₂)₂]⁺[B(R¹⁵)₄]⁻ where R is C₁-C₆ hydrocarbyl.

In a further embodiment, a method is provided for synthesizing anorganometallic complex having the structure of formula (XII)

wherein M, L¹, X¹, X², R¹, and Y are as defined previously, W is anoptionally substituted and/or heteroatom-containing C₁-C₂₀hydrocarbylene linkage, Y is a positively charged Group 15 or Group 16element substituted with hydrogen, C₁-C₁₂ hydrocarbyl, substitutedC₁-C₁₂ hydrocarbyl, heteroatom-containing C₁-C₁₂ hydrocarbyl, orsubstituted heteroatom-containing hydrocarbyl, and Z⁻ is a negativelycharged ion, the method comprising contacting an organometallic complexhaving the structure (XVI)

where R¹⁶ is C₁-C₂₀ hydrocarbyl, with an ionic reagent having thestructure H₂C═CR¹—W—Y⁺Z⁻ under conditions effective to enable crossmetathesis between the transition metal alkylidene group in the complexand the olefinic moiety in the reagent.

Another such method is provided for synthesizing an organometalliccomplex of the invention having the structure of formula (VII)

wherein L¹, L², X¹, X², R¹, W, Y are as defined previously, with Wpreferably being an optionally substituted C₁-C₁₂ alkylene linkage and Ypreferably being a positively charged Group 15 or Group 16 elementsubstituted with and Z is of the formula B(R¹⁵)₄ ⁻ where R¹⁵ is fluoro,aryl, or perfluorinated aryl, the method comprising contacting aruthenium complex having the structure (XVII)

where R¹⁶ is as defined above, with an ionic reagent having thestructure H₂C═CR¹—W—Y⁺Z⁻, under conditions effective to enable crossmetathesis between the ruthenium alkylidene group in the complex and theolefinic moiety in the reagent.

In another embodiment, a method is provided for catalyzing an olefinmetathesis reaction, comprising contacting at least one olefinicreactant with a catalytically effective amount of an organometalliccomplex of the invention under reaction conditions effective to enableolefin metathesis. The metathesis reaction may be ring-closingmetathesis, cross metathesis, ring-opening metathesis polymerization, oracyclic diene metathesis polymerization.

The invention represents a substantial improvement relative to priorGroup 8 transition metal complexes used as olefin metathesis catalysts.Prior such catalysts, including those described in Schrock et al. (1990)J. Am. Chem. Soc. 112:3875, Schrock et al. (2003) Angew. Chem. 115:4740,Schrock et al. (2003) Angew. Chem. Int. Ed. 42:4592, and Trnka et al.(2001) Acc. Chem. Res. 34:18, were either highly active butmoisture-sensitive and intolerant of polar functional groups (e.g.,those described in the Schrock et al. publications) ormoisture-insensitive and tolerant of polar functional groups but lackinghigh activity (e.g., those described by Trnka et al.). By contrast, thepresent complexes and methods provide all of the foregoing advantages,including high activity, moisture-insensitivity, and tolerance of polarfunctional groups. In addition, the initiation time and substrate (i.e.,olefinic reactant) conversion rate can be tuned as desired byappropriately spacing the distance of the cationic species [Y]⁺ from themetal center.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a method for synthesizing catalysts ofthe invention having the structure of formula (II), as described inExamples 1 through 7.

FIG. 2 schematically illustrates a method for synthesizing catalysts ofthe invention having the structure of formula (VII).

FIG. 3 provides the ORTEP diagram of the X-ray crystal structure of(H₂IMes)(PCy₃)Ru═CH(PCy₃)⁺[B(C₆F₅)]⁻, synthesized as described inExample 7.

FIG. 4. illustrates in graph form the relative rates of conversion forthe ring-closing metathesis of diethyldiallylmalonate at 273° K.catalyzed by prior art catalysts and an organometallic complex of theinvention.

FIG. 5 provides the ORTEP diagram of the X-ray crystal structure of[(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[OTf]⁻, synthesized as described in Example 15.

FIG. 6 provides the ORTEP diagram of the X-ray crystal structure of[(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[BPh₄]⁻, synthesized as described in Example16.

DETAILED DESCRIPTION OF THE INVENTION

(I) Definitions and Nomenclature:

It is to be understood that unless otherwise indicated this invention isnot limited to specific reactants, reaction conditions, or the like, assuch may vary. It is also to be understood that the terminology usedherein is for the purpose of describing particular embodiments only andis not intended to be limiting.

As used in the specification and the appended claims, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “a catalyst” or “acomplex” encompasses a combination or mixture of different catalysts orcomplexes as will as a single catalyst or complex, reference to “asubstituent” includes a single substituent as well as two or moresubstituents that may or may not be the same, and the like.

In this specification and in the claims that follow, reference will bemade to a number of terms, which shall be defined to have the followingmeanings:

The phrase “having the formula” or “having the structure” is notintended to be limiting and is used in the same way that the term“comprising” is commonly used.

The term “alkyl” as used herein refers to a linear, branched, or cyclicsaturated hydrocarbon group typically although not necessarilycontaining 1 to about 20 carbon atoms, preferably 1 to about 12 carbonatoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,t-butyl, octyl, decyl, and the like, as well as cycloalkyl groups suchas cyclopentyl, cyclohexyl and the like. Generally, although again notnecessarily, alkyl groups herein contain 1 to about 12 carbon atoms. Theterm “lower alkyl” intends an alkyl group of 1 to 6 carbon atoms, andthe specific term “cycloalkyl” intends a cyclic alkyl group, typicallyhaving 4 to 8, preferably 5 to 7, carbon atoms. The term “substitutedalkyl” refers to alkyl substituted with one or more substituent groups,and the terms “heteroatom-containing alkyl” and “heteroalkyl” refer toalkyl in which at least one carbon atom is replaced with a heteroatom.If not otherwise indicated, the terms “alkyl” and “lower alkyl” includelinear, branched, cyclic, unsubstituted, substituted, and/orheteroatom-containing alkyl and lower alkyl, respectively.

The term “alkylene” as used herein refers to a difunctional linear,branched, or cyclic alkyl group, where “alkyl” is as defined above.

The term “alkenyl” as used herein refers to a linear, branched, orcyclic hydrocarbon group of 2 to about 20 carbon atoms containing atleast one double bond, such as ethenyl, n-propenyl, isopropenyl,n-butenyl, isobutenyl, octenyl, decenyl, tetradecenyl, hexadecenyl,eicosenyl, tetracosenyl, and the like. Preferred alkenyl groups hereincontain 2 to about 12 carbon atoms. The term “lower alkenyl” intends analkenyl group of 2 to 6 carbon atoms, and the specific term“cycloalkenyl” intends a cyclic alkenyl group, preferably having 5 to 8carbon atoms. The term “substituted alkenyl” refers to alkenylsubstituted with one or more substituent groups, and the terms“heteroatom-containing alkenyl” and “heteroalkenyl” refer to alkenyl inwhich at least one carbon atom is replaced with a heteroatom. If nototherwise indicated, the terms “alkenyl” and “lower alkenyl” includelinear, branched, cyclic, unsubstituted, substituted, and/orheteroatom-containing alkenyl and lower alkenyl, respectively.

The term “alkenylene” as used herein refers to a difunctional linear,branched, or cyclic alkenyl group, where “alkenyl” is as defined above.

The term “alkoxy” as used herein intends an alkyl group bound through asingle, terminal ether linkage; that is, an “alkoxy” group may berepresented as —O-alkyl where alkyl is as defined above. A “loweralkoxy” group intends an alkoxy group containing 1 to 6 carbon atoms.Analogously, “alkenyloxy” and “lower alkenyloxy” respectively refer toan alkenyl and lower alkenyl group bound through a single, terminalether linkage, and “alkynyloxy” and “lower alkynyloxy” respectivelyrefer to an alkynyl and lower alkynyl group bound through a single,terminal ether linkage.

The term “aryl,” as used herein and unless otherwise specified, refersto an aromatic substituent containing a single aromatic ring or multiplearomatic rings that are fused together, directly linked, or indirectlylinked (such that the different aromatic rings are bound to a commongroup such as a methylene or ethylene moiety). Preferred aryl groupscontain 5 to 20 carbon atoms, and particularly preferred aryl groupscontain 5 to 14 carbon atoms. Exemplary aryl groups contain one aromaticring or two fused or linked aromatic rings, e.g., phenyl, naphthyl,biphenyl, diphenylether, diphenylamine, benzophenone, and the like.“Substituted aryl” refers to an aryl moiety substituted with one or moresubstituent groups, and the terms “heteroatom-containing aryl” and“heteroaryl” refer to aryl substituent, in which at least one carbonatom is replaced with a heteroatom, as will be described in furtherdetail infra.

The term “aryloxy” as used herein refers to an aryl group bound througha single, terminal ether linkage, wherein “aryl” is as defined above. An“aryloxy” group may be represented as —O-aryl where aryl is as definedabove. Preferred aryloxy groups contain 5 to 20 carbon atoms, andparticularly preferred aryloxy groups contain 5 to 14 carbon atoms.Examples of aryloxy groups include, without limitation, phenoxy,o-halo-phenoxy, m-halo-phenoxy, p-halo-phenoxy, o-methoxy-phenoxy,m-methoxy-phenoxy, p-methoxy-phenoxy, 2,4-dimethoxy-phenoxy,3,4,5-trimethoxy-phenoxy, and the like.

The term “acyl” refers to substituents having the formula —(CO)-alkyl,—(CO)-aryl, or —(CO)-aralkyl, and the term “acyloxy” refers tosubstituents having the formula —O(CO)-alkyl, —O(CO)-aryl, or—O(CO)-aralkyl, wherein “alkyl,” “aryl, and “aralkyl” are as definedabove.

The term “cyclic” refers to alicyclic or aromatic substituents that mayor may not be substituted and/or heteroatom containing, and that may bemonocyclic, bicyclic, or polycyclic. The term “alicyclic” is used in theconventional sense to refer to an aliphatic cyclic moiety, as opposed toan aromatic cyclic moiety, and may be monocyclic, bicyclic, orpolycyclic.

The terms “halo” and “halogen” are used in the conventional sense torefer to a chloro, bromo, and fluoro or iodo substituent.

The term “fluorinated” is used in the conventional sense to refer to thereplacement of a hydrogen atom in a molecule or molecular segment with afluorine atom. The term “perfluorinated” is also used in theconventional sense to refer to a molecule or molecular segment whereinall hydrogen atoms are replaced with fluorine atoms. Thus, a“fluorinated” methyl group includes —CH₂F and —CHF₂ as well as the“perfluorinated” methyl group trifluoromethyl, i.e., —CF₃.

“Hydrocarbyl” refers to univalent hydrocarbyl radicals containing 1 toabout 30 carbon atoms, preferably 1 to about 20 carbon atoms, mostpreferably 1 to about 12 carbon atoms, including linear, branched,cyclic, saturated, and unsaturated species, such as alkyl groups,alkenyl groups, aryl groups, and the like. The term “lower hydrocarbyl”intends a hydrocarbyl group of 1 to 6 carbon atoms, preferably 1 to 4carbon atoms, and the term “hydrocarbylene” intends a divalenthydrocarbyl moiety containing 1 to about 30 carbon atoms, preferably 1to about 20 carbon atoms, most preferably 1 to about 12 carbon atoms,including linear, branched, cyclic, saturated and unsaturated species.The term “lower hydrocarbylene” intends a hydrocarbylene group of 1 to 6carbon atoms. “Substituted hydrocarbyl” refers to hydrocarbylsubstituted with one or more substituent groups, and the terms“heteroatom-containing hydrocarbyl” and “heterohydrocarbyl” refer tohydrocarbyl in which at least one carbon atom is replaced with aheteroatom. Similarly, “substituted hydrocarbylene” refers tohydrocarbylene substituted with one or more substituent groups, and theterms “heteroatom-containing hydrocarbylene” and “heterohydrocarbylene”refer to hydrocarbylene in which at least one carbon atom is replacedwith a heteroatom. Unless otherwise indicated, the term “hydrocarbyl”and “hydrocarbylene” are to be interpreted as including substitutedand/or heteroatom-containing hydrocarbyl and hydrocarbylene moieties,respectively.

The term “heteroatom-containing” as in a “heteroatom-containinghydrocarbyl group” refers to a hydrocarbon molecule or a hydrocarbylmolecular fragment in which one or more carbon atoms is replaced with anatom other than carbon, e.g., nitrogen, oxygen, sulfur, phosphorus orsilicon, typically nitrogen, oxygen or sulfur. Similarly, the term“heteroalkyl” refers to an alkyl substituent that isheteroatom-containing, the term “heterocyclic” refers to a cyclicsubstituent that is heteroatom-containing, the terms “heteroaryl” andheteroaromatic” respectively refer to “aryl” and “aromatic” substituentsthat are heteroatom-containing, and the like. It should be noted that a“heterocyclic” group or compound may or may not be aromatic, and furtherthat “heterocycles” may be monocyclic, bicyclic, or polycyclic asdescribed above with respect to the term “aryl.”

By “substituted” as in “substituted hydrocarbyl,” “substituted alkyl,”“substituted aryl,” and the like, as alluded to in some of theaforementioned definitions, is meant that in the hydrocarbyl, alkyl,aryl, or other moiety, at least one hydrogen atom bound to a carbon (orother) atom is replaced with one or more non-hydrogen substituents.Examples of such substituents include, without limitation: functionalgroups such as halo, hydroxyl, sulfhydryl, C₁-C₂₀ alkoxy, C₂-C₂₀alkenyloxy, C₂-C₂₀ alkynyloxy, C₅-C₂₀ aryloxy, C₆-C₂₀ aralkyloxy, C₆-C₂₀alkaryloxy, acyl (including C₂-C₂₀ alkylcarbonyl (—CO-alkyl) and C₆-C₂₀arylcarbonyl (—CO-aryl)), acyloxy (—O-acyl, including C₂-C₂₀alkylcarbonyloxy (—O—CO-alkyl) and C₆-C₂₀ arylcarbonyloxy (—O—CO-aryl)),C₂-C₂₀ alkoxycarbonyl (—(CO)—O-alkyl), C₆-C₂₀ aryloxycarbonyl(—(CO)—O-aryl), halocarbonyl (—CO)—X where X is halo), C₂-C₂₀alkylcarbonato (—O—(CO)—O-alkyl), C₆-C₂₀ arylcarbonato (—O—(CO)—O-aryl),carboxy (—COOH), carboxylato (—COO⁻), carbamoyl (—(CO)—NH₂),mono-(C₁-C₂₀ alkyl)-substituted carbamoyl (—(CO)—NH(C₁-C₂₀ alkyl)),di-(C₁-C₂₀ alkyl)-substituted carbamoyl (—(CO)—N(C₁-C₂₀ alkyl)₂),mono-(C₅-C₂₀ aryl)-substituted carbamoyl (—(CO)—NH-aryl), di-(C₅-C₂₀aryl)-substituted carbamoyl (—(CO)—N(C₅-C₂₀ aryl)₂), di-N—(C₁-C₂₀alkyl),N—(C₅-C₂₀ aryl)-substituted carbamoyl, thiocarbamoyl (—(CS)—NH₂),mono-(C₁-C₂₀ alkyl)-substituted thiocarbarnoyl (—(CO)—NH(C₁-C₂₀ alkyl)),di-(C₁-C₂₀ alkyl)-substituted thiocarbamoyl (—(CO)—N(C₁-C₂₀ alkyl)₂),mono-(C₅-C₂₀ aryl)-substituted thiocarbamoyl (—(CO)—NH-aryl), di-(C₅-C₂₀aryl)-substituted thiocarbamoyl (—(CO)—N(C₅-C₂₀ aryl)2), di-N—(C₁-C₂₀alkyl),N—(C₅-C₂₀ aryl)-substituted thiocarbanoyl, carbamido(—NH—(CO)—NH₂), cyano(—C≡N), cyanato (—O—C≡N), thiocyanato (—S—C≡N),isocyano (—N+≡C⁻), formyl (—(CO)—H), thioformyl (—(CS)—H), amino (—NH₂),mono-(C₁-C₂₀ alkyl)-substituted amino, di-(C₁-C₂₀ alkyl)-substitutedamino, mono-(C₅-C₂₀ aryl)-substituted amino, di-(C₅-C₂₀aryl)-substituted amino, C₂-C₂₀ alkylamido (—NH—(CO)-alkyl), C₆-C₂₀arylamido (—NH—(CO)-aryl), imino (—CR═NH where R=hydrogen, C₁-C₂₀ alkyl,C₅-C₂₀ aryl, C₆-C₂₀ alkaryl, C₆-C₂₀ aralkyl, etc.), C₂-C₂₀ alkylimino(—CR═N(alkyl), where R=hydrogen, C₁-C₂₀ alkyl, C₅-C₂₀ aryl, C₆-C₂₀alkaryl, C₆-C₂₀ aralkyl, etc.), arylimino (—CR═N(aryl), whereR=hydrogen, C₁-C₂₀ alkyl, C₅-C₂₀ aryl, C₆-C₂₀ alkaryl, C₆-C₂₀ aralkyl,etc.), nitro (—NO₂), nitroso (—NO), sulfo (—SO₂—OH), sulfonato(—SO₂—O⁻), C₁-C₂₀ alkylsulfanyl (—S-alkyl; also termed “alkylthio”),C₅-C₂₀ arylsulfanyl (—S-aryl; also termed “arylthio”), C₁-C₂₀alkyldithio (—S—S-alkyl), C₅-C₂₀ aryldithio (—S—S-aryl), C₁-C₂₀alkylsulfinyl (—(SO)-alkyl), C₅-C₂₀ arylsulfinyl (—(SO)-aryl), C₁-C₂₀alkylsulfonyl (—SO₂-alkyl), C₅-C₂₀ arylsulfonyl (—SO₂-aryl), boryl(—BH₂), borono (—B(OH)₂), boronato (—B(OR)₂ where R is alkyl or otherhydrocarbyl), phosphono (—P(O)(OH)₂), phosphonato (—P(O)(O⁻)₂),phosphinato (—P(O)(O⁻)), phospho (—PO₂), phosphino (—PH₂), silyl (—SiR₃wherein R is hydrogen or hydrocarbyl), and silyloxy (—O-silyl); and thehydrocarbyl moieties C₁-C₂₀ alkyl (preferably C₁-C₁₂ alkyl, morepreferably C₁-C₆ alkyl), C₂-C₂₀ alkenyl (preferably C₂-C₁₂ alkenyl, morepreferably C₂-C₆ alkenyl), C₂-C₂₀ alkynyl (preferably C₂-C₁₂ alkynyl,more preferably C₂-C₆ alkynyl), C₅-C₂₀ aryl (preferably C₅-C₁₄ aryl),C₆-C₂₀ alkaryl (preferably C₆-C₁₆ alkaryl), and C₆-C₂₀ aralkyl(preferably C₆-C₁₆ aralkyl).

In addition, the aforementioned functional groups may, if a particulargroup permits, be further substituted with one or more additionalfunctional groups or with one or more hydrocarbyl moieties such as thosespecifically enumerated above. Analogously, the above-mentionedhydrocarbyl moieties may be further substituted with one or morefunctional groups or additional hydrocarbyl moieties such as thosespecifically enumerated.

The term “olefin metathesis” is used in the now-conventional sense torefer to the metal-catalyzed redistribution of carbon-carbon bonds in areaction involving an olefin.

When a modifier term appears prior to a list of two or more elements, itis intended that the term apply to every element of the list. Forexample, the phrase “substituted alkyl, alkenyl, and aryl” is to beinterpreted as “substituted alkyl, substituted alkenyl, and substitutedaryl.” Analogously, when the term “heteroatom-containing” appears priorto a list of possible heteroatom-containing groups, it is intended thatthe term apply to every member of that group. For example, the phrase“heteroatom-containing alkyl, alkenyl, and aryl” is to be interpreted as“heteroatom-containing alkyl, substituted alkenyl, and substitutedaryl.”

“Optional” or “optionally” means that the subsequently describedcircumstance may or may not occur, so that the description includesinstances where the circumstance occurs and instances where it does not.For example, the phrase “optionally substituted” means that anon-hydrogen substituent may or may not be present on a given atom, and,thus, the description includes structures wherein a non-hydrogensubstituent is present and structures wherein a non-hydrogen substituentis not present.

In the molecular structures herein, the use of bold and dashed lines todenote particular conformation of groups follows the IUPAC convention. Abond indicated by a broken line indicates that the group in question isbelow the general plane of the molecule as drawn, and a bond indicatedby a bold line indicates that the group at the position in question isabove the general plane of the molecule as drawn.

(II) The Organometallic Complexes:

The organometallic complexes of the invention have the structure offormula (I)

wherein M, L¹, L², X¹, X², R¹, W, Y, Z, m and n are as follows.

M, which serves as the transition metal center, is a Group 8 transitionmetal, particularly ruthenium or osmium. In a particularly preferredembodiment, M is ruthenium.

X¹ and X² are anionic ligands, and may be the same or different, or maybe linked together to form a cyclic group, typically although notnecessarily a five- to eight-membered ring. In preferred embodiments, X¹and X² are each independently hydrogen, halide, or one of the followinggroups: C₁-C₂₀ alkyl, C₅-C₂₀ aryl, C₁-C₂₀ alkoxy, C₅-C₂₀ aryloxy, C₂-C₂₀alkoxy-carbonyl, C₆-C₂₀ aryloxycarbonyl, C₂-C₂₀ acyl, C₂-C₂₀ acyloxy,C₁-C₂₀ alkylsulfonato, C₅-C₂₀ arylsulfonato, C₁-C₂₀ alkylsulfanyl,C₅-C₂₀ arylsulfanyl, C₁-C₂₀ alkylsulfinyl, or C₅-C₂₀ arylsulfinyl.Optionally, X¹ and X² may be substituted with one or more moietiesselected from C₁-C₁₂ alkyl, C₁-C₁₂ alkoxy, C₅-C₂₀ aryl, and halide,which may, in turn, with the exception of halide, be further substitutedwith one or more groups selected from halide, C₁-C₆ alkyl, C₁-C₆ alkoxy,and phenyl. In the latter case, i.e., when X¹and X² are substituted,fluoride substituents are preferred, giving rise to fluorinated andperfluorinated anionic ligands. In more preferred embodiments, X¹ and X²are selected from halide, mesylate, tosylate, fluorinated C₂-C₂₀ acyloxy(e.g., trifluoroacetate, CF₃CO₂), fluorinated C₁-C₂₀ alkylsulfonate(e.g., trifluoromethanesulfonate, CF₃SO₃; also referred to as“triflate”), fluorinated C₁-C₂₀ alkoxy (e.g., hexafluoroisopropoxide,(CF₃)₂CHO), and fluorinated C₅-C₂₀ aryloxy (e.g., perfluorophenoxy,C₆F₅O). In the most preferred embodiment, X¹ and X² are each chloride.

R¹ is selected from hydrogen, hydrocarbyl (e.g., C₁-C₂₀ alkyl, C₂-C₂₀alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₀ aryl, C₆-C₂₀ alkaryl, C₆-C₂₀ aralkyl,etc.), substituted hydrocarbyl (e.g., substituted C₁-C₂₀ alkyl, C₂-C₂₀alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₀ aryl, C₆-C₂₀ alkaryl, C₆-C₂₀ aralkyl,etc.), heteroatom-containing hydrocarbyl (e.g., heteroatom-containingC₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₀ aryl, C₆-C₂₀alkaryl, C₆-C₂₀ aralkyl, etc.), and substituted heteroatom-containinghydrocarbyl (e.g., substituted heteroatom-containing C₁-C₂₀ alkyl,C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₅-C₂₀ aryl, C₆-C₂₀ alkaryl, C₆-C₂₀aralkyl, etc.), and functional groups. Typically, R¹ is hydrogen, C₁-C₁₂hydrocarbyl, or substituted C₁-C₁₂ hydrocarbyl, preferably hydrogen orC₁-C₁₂ alkyl, and optimally hydrogen.

L¹and L² are neutral electron donor ligands, and m is zero or 1, meaningthat L² is optional. Examples of suitable L¹ moieties include, withoutlimitation, phosphine, sulfonated phosphine, phosphite, phosphinite,phosphonite, arsine, stilbine, ether (including cyclic ethers), amine,amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, substitutedpyridine (e.g., halogenated pyridine), imidazole, substituted imidazole(e.g., halogenated imidazole), pyrazine (e.g., substituted pyrazine),thioether, and heteroatom-substituted carbene, and examples of suitableL² moieties include, without limitation, phosphine, sulfonatedphosphine, phosphite, phosphinite, phosphonite, arsine, stilbine, ether(including cyclic ethers), amine, amide, imine, sulfoxide, carboxyl,nitrosyl, pyridine, substituted pyridine (e.g., halogenated pyridine),imidazole, substituted imidazole (e.g., halogenated imidazole), pyrazine(e.g., substituted pyrazine), and thioether. Preferred L¹ ligands areN-heterocyclic carbenes and phosphines, and preferred L² ligands arephosphines. Exemplary phosphines are of the formula PR⁵R⁶R⁷, where R⁵,R⁶, and R⁷ are each independently aryl or C₁-C₁₀ alkyl, particularlyprimary alkyl, secondary alkyl, or cycloalkyl. Such phosphines include,for example, tricyclohexylphosphine, tricyclopentylphosphine,triisopropylphosphine, triphenylphosphine, diphenylmethylphosphine, orphenyldimethylphosphine, with tricyclohexylphosphine andtricyclopentylphosphine. It is also to be understood that when complexesof the invention represented as containing a single neutral electrondonor ligand (L¹, and not L²) are in a polar organic solvent or in areaction mixture, the transition metal center may associate with thepolar solvent molecules (e.g., water, ketones, aldehydes, organohalides,or the like) or with a substrate (e.g., acrylonitrile).

W is an optionally substituted and/or heteroatom-containing C₁-C₂₀hydrocarbylene linkage, typically an optionally substituted C₁-C₁₂alkylene linkage, e.g., —(CH₂)_(i)— where i is an integer in the rangeof 1 to 12 inclusive and any of the hydrogen atoms may be replaced witha non-hydrogen substituent as described earlier herein with regard tothe definition of the term “substituted.” The subscript n is zero or 1,meaning that W may or may not be present. In a preferred embodiment, nis zero.

Y is a positively charged Group 15 or Group 16 element substituted withhydrogen, C₁-C₁₂ hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl,heteroatom-containing C₁-C₁₂ hydrocarbyl, or substitutedheteroatom-containing hydrocarbyl. Preferably, Y is a C₁-C₁₂hydrocarbyl-substituted, positively charged Group 15 or Group 16element. Representative Y groups include P(R²)₃, P(R²)₃, As(R²)₃,S(R²)₂, O(R²)₂, where the R² are independently selected from C₁-C₁₂hydrocarbyl; within these, preferred Y groups are phosphines of thestructure P(R²)₃ wherein the R² are independently selected from C₁-C₁₂alkyl and aryl, and thus include, for example, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, t-butyl, cyclopentyl, cyclohexyl, andphenyl. Y can also be a heterocyclic group containing the positivelycharged Group 15 or Group 16 element. For instance, when the Group 15 orGroup 16 element is nitrogen, Y may be an optionally substitutedpyridinyl, pyrazinyl, or imidazolyl group.

Z⁻ is a negatively charged counterion associated with the cationiccomplex, and may be virtually any anion, so long as the anion is inertwith respect to the components of the complex and the reactants andreagents used in the metathesis reaction catalyzed. Preferred Z⁻moieties are weakly coordinating anions, such as, for instance,[B(C₆F₅)₄]⁻, [BF₄]⁻, [B(C₆H₆)₄]⁻, [CF₃S(O)₃]⁻, [PF₆]⁻, [SbF₆]⁻,[AlCl₄]⁻, [FSO₃]⁻, [CB₁₁H₆Cl₆]⁻, [CB₁₁H₆Br₆]⁻, and [SO₃F:SbF₅]⁻.Preferred anions suitable as Z⁻ are of the formula B(R¹⁵)₄ ⁻ where R¹⁵is fluoro, aryl, or perfluorinated aryl, typically fluoro orperfluorinated aryl. Most preferred anions suitable as Z⁻ are BF₄ ⁻ andB(C₆F₅)⁻, optimally the latter.

It should be emphasized that any two or more of X¹, X², L¹, L², R¹, W,and Y can be taken together to form a cyclic group, as disclosed, forexample, in U.S. Pat. No. 5,312,940 to Grubbs et al. When any of X¹, X²,L¹, L², R¹, W, and Y are linked to form cyclic groups, those cyclicgroups may be five- or six-membered rings, or may comprise two or threefive- or six-membered rings, which may be either fused or linked. Thecyclic groups may be aliphatic or aromatic, and may beheteroatom-containing and/or substituted, as explained in part (I) ofthis section.

One group of exemplary catalysts encompassed by the structure of formula(I) are those wherein m and n are zero, such that the complex has thestructure of formula (II)

Possible and preferred X¹, X², and L¹ ligands are as described earlierwith respect to complexes of formula (I), as are possible and preferredY⁺ and Z⁻ moieties. M is Ru or Os, preferably Ru, and R¹ is hydrogen orC₁-C₁₂ alkyl, preferably hydrogen.

In formula (II)-type catalysts, L¹ is preferably a heteroatom-containingcarbene ligand having the structure of formula (III)

such that the complex (II) is then has the structure of formula (IV)

wherein X¹, X², R¹, R², Y, and Z are as defined previously, and theremaining substituents are as follows:

Z¹ and Z² are heteroatoms typically selected from N, O, S, and P. SinceO and S are divalent, j is necessarily zero when Z¹ is O or S, and k isnecessarily zero when Z² is O or S. However, when Z¹ is N or P, then jis 1, and when Z² is N or P, then k is 1. In a preferred embodiment,both Z¹ and Z² are N.

Q¹, Q², Q³, and Q⁴ are linkers, e.g., C₁-C₁₂ hydrocarbylene, substitutedC₁-C₁₂ hydrocarbylene, heteroatom-containing C₁-C₁₂ hydrocarbylene,substituted heteroatom-containing C₁-C₁₂ hydrocarbylene, or —(CO)—, andw, x, y, and z are independently zero or 1, meaning that each linker isoptional. Preferably, w, x, y, and z are all zero.

R³, R^(3A), R⁴, and R^(4A) are independently selected from hydrogen,hydrogen, C₁-C₂₀ hydrocarbyl, substituted C₁-C₂₀ hydrocarbyl,heteroatom-containing C₁-C₂₀ hydrocarbyl, and substitutedheteroatom-containing C₁-C₂₀ hydrocarbyl.

Preferably, w, x, y, and z are zero, Z¹ and Z¹ are N, and R^(3A) andR^(4A) are linked to form —Q—, such that the complex has the structureof formula (V)

wherein R³ and R⁴ are defined above, with preferably at least one of R³and R⁴, and more preferably both R³ and R⁴, being alicyclic or aromaticof one to about five rings, and optionally containing one or moreheteroatoms and/or substituents. Q is a linker, typically ahydrocarbylene linker, including C₁-C₁₂ hydrocarbylene, substitutedC₁-C₁₂ hydrocarbylene, heteroatom-containing C₁-C₁₂ hydrocarbylene, orsubstituted heteroatom-containing C₁-C₁₂ hydrocarbylene linker, whereintwo or more substituents on adjacent atoms within Q may be linked toform an additional cyclic structure, which may be similarly substitutedto provide a fused polycyclic structure of two to about five cyclicgroups. Q is often, although not necessarily, a two-atom linkage or athree-atom linkage, e.g., —CH₂—CH₂—, —CH(Ph)-CH(Ph)- where Ph is phenyl;═CR—N═, giving rise to an unsubstituted (when R=H) or substituted(R=other than H) triazolyl group; or —CH₂—SiR₂—CH₂— (where R is H,alkyl, alkoxy, etc.).

In a more preferred embodiment, Q is a two-atom linkage having thestructure —CR⁸R⁹—CR¹⁰R¹¹— or —CR⁸═CR¹⁰—, preferably —CR⁸R⁹—CR¹⁰R¹¹—,wherein R⁸, R⁹, R¹⁰, and R¹¹ are independently selected from hydrogen,C₁-C₁₂ hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl,heteroatom-containing C₁-C₁₂ hydrocarbyl, substitutedheteroatom-containing C₁-C₁₂ hydrocarbyl, and functional groups asdefined in part (I) of this section. Examples of functional groups hereinclude carboxyl, C₁-C₂₀ alkoxy, C₅-C₂₀ aryloxy, C₂-C₂₀ alkoxycarbonyl,C₂-C₂₀ alkoxycarbonyl, C₂-C₂₀ acyloxy, C₁-C₂₀ alkylthio, C₅-C₂₀arylthio, C₁-C₂₀ alkylsulfonyl, and C₁-C₂₀ alkylsulfinyl, optionallysubstituted with one or more moieties selected from C₁-C₁₀ alkyl, C₁-C₁₀alkoxy, C₅-C₂₀ aryl, hydroxyl, sulfhydryl, formyl, and halide.Alternatively, any two of R⁸, R⁹, R¹⁰, and R¹¹ may be linked together toform a substituted or unsubstituted, saturated or unsaturated ringstructure, e.g., a C₄-C₁₂ alicyclic group or a C₅ or C₆ aryl group,which may itself be substituted, e.g., with linked or fused alicyclic oraromatic groups, or with other substituents.

When R³ and R⁴ are aromatic, they are typically although not necessarilycomposed of one or two aromatic rings, which may or may not besubstituted, e.g., R³ and R⁴ may be phenyl, substituted phenyl,biphenyl, substituted biphenyl, or the like. In one preferredembodiment, R³ and R⁴ are the same and have the structure (VI)

in which R¹², R¹³, and R¹⁴ are each independently hydrogen, C₁-C₂₀alkyl, substituted C₁-C₂₀ alkyl, C₁-C₂₀ heteroalkyl, substituted C₁-C₂₀heteroalkyl, C₅-C₂₀ aryl, substituted C₅-C₂₀ aryl, C₅-C₂₀ heteroaryl,C₅-C₃₀ aralkyl, C₅-C₃₀ alkaryl, or halide. Preferably, R¹², R¹³, and R¹⁴are each independently hydrogen, C₁-C₁₀ alkyl, C₁-C₁₀ alkoxy, C₅-C₁₄aryl, substituted C₅-C₁₄ aryl, or halide. More preferably, R³ and R⁴ aremesityl (2,4,6-trimethylphenyl).

Exemplary organometallic complexes having the general structure (II) arethose wherein:

L¹ is 1,3-dimesitylimidazole-2-ylidene (IMes) or1,3-dimesityl-4,5-dihydroimidazol-2-ylidene (H₂IMes);

X¹ and X² are chloro;

Y is P(R²)₃, wherein the R² are independently selected from C₁-C₆ alkyland phenyl; and

Z⁻ is BF₄ ⁻ or B(C₆F₅)⁻.

It will be appreciated that organometallic complexes having thestructure of formula (I) wherein m is zero (such that no L² is present),including but not limited to complexes of formula (II), are highlyactive olefin metathesis catalysts. Without wishing to be bound bytheory, it is presumed that the high activity is due to the absence of asecond electron-donating ligand. That is, it has been shownexperimentally (Dias et al. (1997) J. Am. Chem. Soc. 119:3887 and Adhartet al. (2000) J. Am. Chem. Soc. 122:8204) and computationally (Adhart etal. (2004) J. Am. Chem. Soc. 126:3496 and Cavallo (2002) J. Am. Chem.Soc. 124:8965) that in the known catalysts (PCy₃)₂(Cl)₂Ru═CHPh (D) and(IMesH₂)(PCy₃)(Cl)₂Ru═CHPh (E)

(wherein “Cy” represents cyclohexyl, “Mes” represents mesitylene, and“Ph” represents phenyl), the reactive species is the 14-electronalkylidene complex Cl₂(L)Ru═C(H)Ph, wherein L is tricyclohexylphosphineor H₂IMes, respectively. This reactive species is formed upondissociation of the second electron donor ligand(tricyclohexylphosphine, in the aforementioned examples), a process thatis reversible. It will thus be appreciated that with catalysts such asthose of formula (II), the absence of a second electron donor ligandimproves the kinetics of initiation by circumventing the initiation stepcompletely.

Another group of catalysts encompassed by the structure of formula (I)are those wherein M is Ru or Os, preferably Ru, R¹ is hydrogen or C₁-C₁₂alkyl, preferably hydrogen, and both m and n are 1, such that thecomplex has the structure of formula (VII)

As with complexes of formula (II), possible and preferred X¹, X², L¹,and L² ligands in complexes of formula (VII) are as described earlierwith respect to complexes of formula (I), as are possible and preferredW, Y⁺, and Z⁻ moieties.

Exemplary organometallic complexes having the general structure (VII)are those wherein:

L¹ is 1,3-dimesitylimidazole-2-ylidene (IMes) or1,3-dimesityl-4,5-dihydroimidazol-2-ylidene (H₂IMes);

L² is selected from tricyclohexylphosphine, tricyclopentylphosphine,triisopropylphosphine, triphenylphosphine, diphenylmethylphosphine, andphenyldimethylphosphine;

W is an optionally substituted C₁-C₁₂ alkylene linkage;

X¹ and X² are chloro;

Y is P(R²)₃, wherein the R² are independently selected from C₁-C₆ alkyland phenyl; and

Z⁻ is BF₄ ⁻ or B(C₆F₅)⁻.

Representative organometallic complexes of the invention thus include,without limitation, the following specific structures 1 through 12:

The organometallic complexes of the invention have been shown to bestable to oxygen and ambient moisture as well as thermally stable. Itadditionally appears that these catalysts may be stable indefinitely inthe solid state when stored at room temperature. Metathesis reactionswith functionalized olefins also proceed efficiently, providing thedesired product at a high yield with relative small quantities of thecatalytic complex.

(III) Synthesis of the Complexes:

The organometallic complexes of the invention are synthesized from Group8 transition metal carbenes having the structure of formula (XVI)

or from Group 8 transition metal carbides prepared therefrom, wherein M,L¹, L², X¹, and X² are as defined previously, and R¹⁶ is C₁-C₂₀hydrocarbyl.

For example, an organometallic complex having the structure of formula(XI)

wherein M is a Group 8 transition metal, L¹ is a neutral electron donorligand, X¹ and X² are anionic ligands, R¹ is hydrogen, C₁-C₁₂hydrocarbyl, or substituted C₁-C₁₂ hydrocarbyl, Y is a positivelycharged Group 15 or Group 16 element substituted with hydrogen, C₁-C₁₂hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl, heteroatom-containingC₁-C₁₂ hydrocarbyl, or substituted heteroatom-containing hydrocarbyl,and Z⁻ is a negatively charged ion, may be synthesized by contacting aGroup 8 transition metal carbide having the structure (XIII)

with an ionic reagent of the formula [R¹]⁺[Z]⁻. The [R¹]⁺ moiety in theionic reagent is typically hydrogen, and may be associated with a polarsolvent (as in [H(Et₂O)₂][B(C₆F₅)₄]⁻; see Jutzi et al. (2000), citedsupra). Preferred Z⁻ moieties, as noted earlier herein, are weaklycoordinating anions, such as, for instance, [B(C₆F₅)₄]⁻, [BF₄]⁻,[B(C₆H₆)₄]⁻, [CF₃S(O)₃]⁻, [PF₆]⁻, [SbF₆]⁻, [AlCl₄]⁻, [FSO₃]⁻,[CB₁₁H₆Cl₆]⁻, [CB₁₁H₆Br₆]⁻, and [SO₃F:SbF₅]⁻, with [B(C₆F₅)₄]⁻ and[BF₄]⁻ particularly preferred. Suitable ionic reagents thus include,without limitation, [H(Et₂O)₂][B(C₆F₅)₄], [H(Et₂O)₂][BF₄], BF₃/HF,HB(C₆H₆)₄, CF₃S(O)₃H, HF—PF₅, HF—SbF₅, CHCCl₃:AlCl₃, HSO₃F:SbF₅, andFSO₃H.

The invention also provides a method for synthesizing an organometalliccomplex having the structure of formula (II)

wherein L¹, X¹, X², R¹, and Y are as defined previously, with Ypreferably being a C₁-C₁₂ hydrocarbyl-substituted, positively chargedGroup 15 or Group 16 element, and Z⁻ is of the formula B(R¹⁵)₄ ⁻ whereR¹⁵ is fluoro, aryl, or perfluorinated aryl, the method comprising:

(a) contacting (i) a ruthenium complex having the structure (XIV)

where R¹⁶ is C₁-C₂₀ hydrocarbyl, with (ii) a reagent effective toconvert the ruthenium complex to the ruthenium carbide (XV)

and

(b) contacting the ruthenium carbide with a protonating reagent of theformula [H(OR₂)₂]⁺[B(R¹⁵)₄]⁻ where R is C₁-C₆ hydrocarbyl.

The following scheme illustrates this synthesis:

In the initial step of the reaction, the ruthenium complex (VIII)((X¹X²)(L¹Y)Ru═CHR¹⁶) is contacted with a reagent (identified as“Reagent A” in the scheme) effective to convert the ruthenium complex tothe ruthenium carbide (IX) ((X¹X²)(Y)Ru≡C:). As indicated in theexamples, an exemplary reagent for this purpose is the methylenecyclopropane olefin known as Feist's ester, having the structure

The reaction between complex (VIII) and Feist's ester is a metathesisreaction that results in elimination of diethyl flumarate(EtO₂C—CH═CH—CO₂Et) and generation of the carbide (IX). Subsequentreaction involves protonation of the carbide (IX) with the electrophilicreagent [H(OR₂)₂]⁺[B(R¹⁵)₄]⁻ and transfer of the ligand Y to theprotonated carbide carbon atom, resulting in complex (X). See FIG. 1.

In a further embodiment, a method is provided for synthesizing anorganometallic complex having the structure of formula (XII)

wherein M, L¹, X¹, X², R¹, and Y are as defined previously, W is anoptionally substituted and/or heteroatom-containing C₁-C₂₀hydrocarbylene linkage, Y is a positively charged Group 15 or Group 16element substituted with hydrogen, C₁-C₁₂ hydrocarbyl, substitutedC₁-C₁₂ hydrocarbyl, heteroatom-containing C₁-C₁₂ hydrocarbyl, orsubstituted heteroatom-containing hydrocarbyl, and Z⁻ is a negativelycharged ion, the method comprising contacting an organometallic complexhaving the structure (XVI)

where R¹⁶ is C₁-C₂₀ hydrocarbyl, with an ionic reagent having thestructure H₂C═CR¹—W—Y⁺Z⁻ under conditions effective to enable crossmetathesis between the transition metal alkylidene group in the complexand the olefinic moiety in the reagent. As illustrated in the reactionof Scheme 2, in FIG. 2, the complex (XVI) is in equilibrium with acomplex lacking the L² moiety. Therefore, the aforementioned synthesisis also useful for preparing complexes of formula (I) wherein m is zeroand n is 1.

In a further embodiment, the invention provides a method forsynthesizing an organometallic complex of the invention having thestructure of formula (VII)

wherein L¹, L², X¹, X², R¹, W, Y are as defined previously, with Ypreferably being a C₁-C₁₂ hydrocarbyl-substituted, positively chargedGroup 15 or Group 16 element, and Z⁻ is of the formula B(R¹⁵)₄ ⁻ whereR¹⁵ is fluoro, aryl, or perfluorinated aryl, the method comprisingcontacting a ruthenium complex having the structure (XVII)

where R¹⁶ is as defined above, with an ionic reagent having thestructure H₂C═CR¹—W—Y⁺Z⁻, under conditions effective to enable crossmetathesis between the ruthenium alkylidene group in the complex and theolefinic moiety in the reagent. This reaction is illustrated by thescheme set forth in FIG. 2.(IV) Utility:

The organometallic complexes of the invention are useful in thecatalysis of olefin metathesis reactions, including ROMP, RCM, ADMET,and XMET reactions. Accordingly, the invention provides, in a furtherembodiment, a method for catalyzing an olefin metathesis reaction, themethod comprising contacting an olefinic reactant with a catalyticallyeffective amount of an organometallic complex of the invention underreaction conditions effective to enable olefin metathesis. ROMP iscarried out, by definition, with a cyclic olefin substrate, RCM andADMET with acyclic dienes, and XMET with two olefinic reactants.

The reaction conditions are those normally used in olefin metathesisreactions catalyzed by the Grubbs family of metathesis catalysts, e.g.,as described in U.S. Pat. Nos. 5,312,940, 5,342,909, 5,831,108,5,969,170, 6,111,121, and 6,211,391 to Grubbs et al. The complexes maybe dissolved in the reaction medium or attached to a solid support; asunderstood in the field of catalysis, suitable solid supports may be ofsynthetic, semi-synthetic, or naturally occurring materials, which maybe organic or inorganic, e.g., polymeric, ceramic, or metallic.Attachment to the support may through ionic interaction or via acovalent linkage, and the covalent linkage may be direct or indirect; ifindirect, the linkage will typically be between a functional group on asupport surface and a ligand or substituent on the catalytic complex.

The complexes are also useful in the synthesis of “Grubbs-Hoveyda”catalysts in which a single moiety is covalently bound to the carbenecarbon atom and contains a functionality that coordinates to thetransition metal center. See Kingsbury et al. (1999) J. Am. Chem. Soc.121:791; Hoveyda (1999) J. Am. Chem. Soc. 121:791; and Garber et al.(2000) J. Am. Chem. Soc. 122:8168. Such a reaction is illustrated in thefollowing scheme:

In the above scheme, L¹, X¹, X², R¹, Y, and Z⁻ are as defined earlierherein; R¹ is usually hydrogen; J is a heteroatom that is capable ofcoordinating to Ru, e.g., O, S, N, etc., preferably O; R¹⁷ is C₁-C₁₂hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl, heteroatom-containingC₁-C₁₂ hydrocarbyl, or substituted heteroatom-containing hydrocarbyl,preferably C₁-C₆ alkyl; and v is 1 or 2, representing the number of R¹⁷substituents bound to J.

A specific example of such a reaction is the following:

See Romero et al. (2004) Angew. Chem. Int. Ed. 43:6161-6165.

It is to be understood that while the invention has been described inconjunction with the preferred specific embodiments thereof, that theforegoing description as well as the examples that follow are intendedto illustrate and not limit the scope of the invention. Other aspects,advantages and modifications within the scope of the invention will beapparent to those skilled in the art to which the invention pertains.

In the following examples, efforts have been made to ensure accuracywith respect to numbers used (e.g., amounts, temperature, etc.) but someexperimental error and deviation should be accounted for. Unlessindicated otherwise, temperature is in degrees C and pressure is at ornear atmospheric.

Experimental:

The equipment and general procedures used in the Examples herein, aswell as sources or syntheses of all reagents and starting materials,were as follows:

Argon-filled Innovative Technology System One dryboxes were used tostore air and moisture sensitive compounds, and for manipulation of airsensitive materials. Reactions were performed either on a doublemanifold vacuum line using standard Schlenk techniques or under an argonatmosphere in the drybox for small-scale reactions.Diethyldiallylmalonate was purchased from Aldrich and used withoutfurther purification. CH₂Cl₂ was predried and stored in glass bombs overCaH₂ and distilled immediately prior to use. Pentane was stored anddried over a sodium mirror using benzophenone ketyl as indicator andvacuum distilled prior to use. CD₂Cl₂ was purchased from CambridgeIsotopes, dried over CaH₂, and stored in appropriate glass bombs aftervacuum distillation.

Nuclear magnetic resonance (NMR) spectra were obtained on Bruker ACE-200(¹H, 200.134 MHz), AMX 300 (¹H 300.138, ¹⁹F 282.371 MHz) and BAM-400 (¹H400.134 MHz, ¹³C 100.614 MHz, ¹¹B 128.377 MHz). All ¹H and ¹³C spectrawere referenced externally to Me₄Si at 0 ppm by referencing the residualsolvent peak. ¹¹B NMR spectra were referenced to BF₃·Et₂O at 0 ppm,while ¹⁹F spectra were referenced externally to C₆F₆ at −163 ppmrelative to CFCl₃ at 0 ppm. Elemental analyses were performed using aControl Equipment Corporation 440 Elemental Analyzer.

(i-Pr₃P)₂Cl₂Ru═CHPh (1a) and (Cy₃P)₂Cl₂Ru═CHPh (1b) were preparedaccording to published procedures. (H₂IMes)(Cy₃P)Cl₂Ru═CHPh (1c) wasobtained from Materia, Inc. (Pasadena, Calif.). The Schrock Catalyst waspurchased from Strem. Feist's acid was prepared according to theprocedure described by Gilchrist and Rees (Gilchrist et al. (1968) J.Chem. Soc. (C), p. 769), starting from the commercially available ethylisodehydracetate (97%, Acros Organics), following the describedbromination to obtain ethyl5-bromo-2,4-dimethyl-6-oxopyran-3-carboxylate. This a-pyrone wassaponified following the reported procedure to obtain multigramquantities of Feist's acid. Fischer esterification of the diacid wasaccomplished by dissolving pale yellow Feist's acid in methanol andadding 2-3 drops of concentrated sulfuric acid. Upon stirring overnightthe solution was worked up by removing the solvent in a rotavaporatorleaving a pale yellow oil. The oil was redissolved in diethyl ether andtreated twice with a 5% wt. solution of NaHCO₃, twice with distilledwater, and dried over MgSO₄. Upon filtration and evaporation of thesolvent a pale yellow oil was obtained, corresponding to pure Feist'sdimethyl ester as judged by ¹H NMR spectroscopy. The yield wasquantitative. Additionally, solidification of the oil can be induced bycooling at −78° C. under vacuum. Upon thaw at room temperature the oilbecomes a more manageable solid. The dimethyl ester was stored in afreezer due to its low melting point.

Example 1 through 7 describe the synthesis and characterization of thecomplexes prepared in Scheme 1, in FIG. 1.

EXAMPLE 1 Preparation of (i-Pr₃P)₂Cl₂Ru═C: (2a)

In the glovebox, a 50 mL round bottom flask equipped with a stir bar wascharged with (i-Pr₃P)₂Cl₂Ru═CHPh (1a, 1.00 g, 1.71 mmol), which wasdissolved in ca. 15 ml of dry CH₂Cl₂. To this solution, 0.291 g (1.71mmol) of Feist's ester dissolved in ca. 5 ml of CH₂Cl₂ were added atonce via pipette with stirring. Within 1 minute, the color of thesolution changes from purple to brown; stirring was continued foradditional 20 minutes. The flask was then connected to a vacuum line andthe solvent removed to dryness. Drying was continued for ca. 30additional minutes to remove most of the styrene by-product. The flaskwas then opened to air and the solid residue was transferred to asublimation apparatus, where the majority of the flumarate by-productwas removed at 50-60° C. under dynamic vacuum for 1.5 hours. At thispoint some traces of organic material might remain (Feist's ester,styrene or fumarate, all <5%) which can be eliminated by suspending thecomplex in wet pentane, stirring for 1 minute and decanting thesupernatant. By repeating this process twice, a brown solidcorresponding to analytically pure carbide was obtained. Yield: 825 mg(96%). ¹H NMR (CD₂Cl₂, 25° C.): d 1.43 (dd, 36H, (CH₃)—CH—P,³J_(H-H)=7.2 Hz, ³J_(P-H)=14.1 Hz), d 2.71-2.79 (second order multiplet,6H, (CH₃)—CH—P). ³¹P{¹H} NMR (CD₂Cl₂, 25° C.)=d 46.9 (s, Ru—P^(i)Pr₃).¹³C{¹H} NMR (CD₂Cl₂, 25° C.): d 19.81 (s, (CH₃)—CH—P), 22.94 (app. t,(CH₃)—CHP,“J_(C-P)”=13.8 Hz), d 472.9 (Ru≡C).

EXAMPLE 2 Preparation of (Cy₃P)₂Cl₂Ru≡C: (2b)

Using a procedure similar to the one outlined for 2a in Example 1, 2bwas obtained in 90-95% yield. Spectral parameters matched thosepreviously reported (i.e., by Carlson (2002) J. Am. Chem. Soc.124:1580).

EXAMPLE 3 Preparation of (H₂IMes)(Cy₃P)Cl₂Ru≡C: (2c)

In the glovebox, a 50 ml round bottom flask equipped with a stir bar wascharged with (H₂IMes)(Cy₃P)Cl₂Ru═CHPh (1c, 1.50 g, 1.76 mmol), which wasdissolved in ca 20 ml of dry CH₂Cl₂. To this solution, 0.300 g (1.76mmol) of Feist's ester dissolved in ca. 10 ml of CH₂Cl₂ were added atonce via pipette with stirring. By contrast to the preparations of 2a-b,no immediate visible change was observed and the solution was stirredovernight (separate NMR experiments indicated that at thisconcentration, the reaction takes ca. 4 hrs. to reach completion).Work-up procedures were identical to those described above for 2a-b,resulting in a brown solid corresponding to pure carbide 2c wasobtained. Yield: 1.22 g (90%).

EXAMPLE 4 Synthesis of [(i-Pr₃P)Cl₂Ru═CH(Pi-Pr₃)]⁺[B(C₆F₅)₄]⁻ (3a)

In the glovebox, (i-Pr₃P)₂Cl₂Ru≡C: (2a, 400 mg, 0.793 mmol) and[H(Et₂O)₂]⁺[B(C₆F₅)₄]⁻ (657 mg, 0.793 mmol) were weighed into a 50 mlround bottom flask. The flask was then fitted with a glass connectorwith a Kontes valve and attached to the vacuum line. The flask wasevacuated and CH₂Cl₂ (20 ml) was condensed onto the solids at

−78° C., using a dry ice/acetone cooling bath. The solution was thenallowed to warm to room temperature and stirred for an additional hour.The solvent was then removed under vacuum leaving a solid residue. Thesystem was then placed in the glovebox and the solid residue redissolvedin ca 8 ml of CH₂Cl₂ and transferred to a glass vial. The solution waslayered with pentane and allowed to diffuse at room temperatureovernight, yielding burgundy crystals of[(^(i)Pr₃P)Cl₂Ru═CH(P^(i)Pr₃)][B(C₆F₅)₄]. The yield is improved bycooling to −35° C. after diffusion has taken place. Yield: 895 mg, 95%.¹H NMR (CD₂Cl₂, 25° C.): d 1.38 (dd, 18H, Ru═CH—PCH(CH₃)₂, ³J_(H-H)=7.3Hz, ³J_(P-H)=16.5 Hz), d 1.42 (dd, 18H, Ru—PCH(CH₃), ³J_(H-H)=7.1 Hz,³J_(P-H)=15.7 Hz), d 2.69-2.63 (second order multiplet, 3H, (CH₃)—CH—P,³J_(H-H)=7.1 Hz), d 3.00-2.93 (second order multiplet,3H, (CH₃)—CH—P,³J_(H-H)=7.2 Hz), d 17.35 (dd, 1H, Ru═CH, ²J_(P-H)=36 Hz, ³J_(P-H)=1.8Hz). ¹³P{¹H} NMR (CD₂Cl₂, 25° C.)=d 97.6 (s, 1P, Ru—P^(i)Pr₃), d 57.6(s, 1P, Ru═CH—P^(i)Pr₃). ¹¹B NMR=d-17.5 (s, B(C₆F₅)₄). ¹³C{¹H} NMR(CD₂Cl₂, 25° C.):d 17.7 (s, (CH3)—CH—P), d 19.5 (s, (CH₃)—CH—P), 22.0(d, (CH₃)—CH—P, ¹J_(C-P)=39.6 Hz), d 27.6 (d, (CH₃)—CH—P, ¹J_(C-P)=26.7Hz), d 136.3 (dt,¹J_(C-F)=244.5 Hz) 138.3 (dt ¹J_(C-F)=244.8 Hz) and148.2 (d, ¹J_(C-F)=240.6 Hz) all B(C₆F₅)₄ signals, d 240.5 (broad,Ru═CH).

EXAMPLE 5 Synthesis of [(i-Pr₃P)Cl₂Ru═CH(PiPr₃)]⁺(BF₄)⁻

This example describes preparation of a complex analogous to thatprepared in the preceding example, but as the BF₄ ⁻ salt instead of theB(C₆F₅)₄ ⁻ salt:

The compound (i-Pr₃P)₂Cl₂Ru≡C: (2a, 271 mg, 0.537 mmol) was weighed intoa two-neck 50 ml round bottom flask equipped with a stir bar and aseptum in the lateral neck, and the system was evacuated in the vacuumline. CH₂Cl₂ (20 ml) was condensed onto the solid and the system warmedup to room temperature. Then, a 54% wt. solution of HBF₄ in diethylether (74 mL, 0.537 mmol) was injected at room temperature and animmediate change to a darker brown-green color was observed. Thesolution was stirred for 1 hour at which time the solvent was removedunder vacuum. The system was transferred to the glovebox and the solidresidue obtained after evaporation was redissolved in the minimal amountof CH₂Cl₂ (ca. 2 ml). Addition of pentane results in the precipitationof a green microcrystalline solid. The solvent was decanted via pipetteand the solid dried under high vacuum. Yield: 224 mg, 70%. ¹H NMR(CD₂Cl₂, 25° C.): d 1.38 (dd,18H, (CH₃)—CH—P, ³J_(P-H)=6.8 Hz,³J_(H-H)=5.5 Hz), d 1.42 (dd, 18H, (CH₃)—CH—P, ³J_(P-H)=7.0 Hz,³J_(H-H)=4.3 Hz), d 2.69-2.80 (second order multiplet, 3H, (CH₃)—CH—P),d 3.17-3.06 (second order multiplet, 3H, (CH₃)—CH—P), d 17.65 (d, 1H,Ru═CH, ²J_(P-H)=35.5 Hz). ³¹P{¹H} NMR (CD₂Cl₂, 25° C.)=d 97.8 (s, 1P,Ru—P^(i)Pr₃), d 58.5 (s, 1P, Ru═CH—P^(i)Pr₃). ¹¹B NMR=d-1.9 (s, BF₄).

EXAMPLE 6 Synthesis of [(Cy₃P)Cl₂Ru═CH(PCy₃)]⁺[B(C₆F₅)₄]⁻ (3b)

(Cy₃P)₂Cl₂Ru≡C: (2b, 150 mg, 0.201 mmol) and [H(Et₂O)₂]⁺[B(C₆F₅)₄]⁻ (166mg, 0.201 mmol) were placed into a 25 ml round bottom flask, which wasfitted with a glass connector with a Kontes valve and attached to thevacuum line. The flask was evacuated and CH₂Cl₂ (15 ml) was vacuumtransferred onto the solids at −78° C. The system was warmed to roomtemperature and stirred for 1 hour. The solvent was then removed undervacuum leaving a brown residue. Pentane (20 ml) was vacuum transferredonto the residue and the system was sonicated for 5 minutes, leaving agreen-purple residue. After allowing the solid to settle, the solventwas decanted via cannula, and the purple powder left was dried underfull vacuum overnight. Yield: 250 mg, 87%. Alternatively, the productcan be recrystallized by dissolving in CH₂Cl₂ (10 ml) and layering withpentane (10 ml). Upon diffusion of the two phases for 3-4 days, darkpurple crystals are obtained in virtually quantitative yield. ¹H NMR(CD₂Cl₂, 25° C.): d 1.18-1.96 (complex set of multiplets, 66H,P(C₆H₁₁)₃), d 2.29-2.41 (m, 3H, P(C₆H₁₁)₃), d 2.60-2.72 (m, 3H,P(C₆H₁₁)₃), d 17.45 (dd, 1H, Ru═CH, ²J_(P-H)=36.6 Hz, ³J_(P-H)=1.6 Hz).³¹P{¹H} NMR (CD₂Cl₂, 25° C.): d 56.3 (s, 1P, Ru═CH(PCy₃)), d 88.7 (s,1P, Cy₃P—Ru). ¹¹B{¹H} NMR (CD₂Cl₂, 25° C.): d-17.4.

EXAMPLE 7 Synthesis of [(H₂IMes)Cl₂Ru═CH(PCy₃)]⁺[B(C₆F₅)₄]⁻ (3c)

(H₂IMes)(Cy₃P)Cl₂Ru≡C (2c, 80 mg, 0.10 mmol) and [H(Et₂O)₂]⁺[B(C₆F₅)₄]⁻(86 mg, 0.10 mmol) were placed into a 25 ml round bottom flask, whichwas fitted with a glass connector with a Kontes valve and attached tothe vacuum line. The flask was evacuated and CH₂Cl₂ (10 ml) was vacuumtransferred onto the solids at −78° C. The system was warmed to roomtemperature and stirred for 1 hour. The solvent was then removed undervacuum leaving a brown residue. Pentane (20 ml) was vacuum transferredonto the residue and the system was sonicated for 5 minutes, leaving abrown suspension. After allowing the solid to settle, the solvent wasdecanted via cannula, and the brown powder left was dried under fullvacuum for 1 hour. Yield: 150 mg, 95%. ¹H NMR (CD₂Cl₂, 25° C.): d1.26-1.11 (m, XH, P(C₆H₁₁)₃), d 1.83 broad m, XH, P(C₆H₁₁)₃), d 2.37 (s,12H, o-CH₃-Mes),d 2.38 (s, 6H,p-CH₃-Mes), d 4.21 (s, 4H, CH₂-CH₂ bridgein IMes), d 7.01 (s, 4H, m-H-Mes), d 17.7 (d, 1H, Ru═CH). ³¹P{¹H} NMR(CD₂Cl₂, 25° C.): d 54.05 (Ru═CH(PCy₃)). ¹¹B{¹H} NMR (CD₂Cl₂, 25° C.):d-17.4. The structure of the compound in the solid state was determinedby x-ray diffraction methods and is shown in FIG. 4 with selected bondlengths and angles. In FIG. 4, selected bond distances (Å) are asfollows: Ru—C(1), 1.817(2); Ru—C(2), 1.988(2); Ru—Cl(1), 2.2951(5);Ru—Cl(2), 2.2809(5); P—C(1), 1.805(2). Selected bond angles (°):C(1)—Ru—C(2), 100.07(7); Cl(1)—Ru—Cl(2), 150.51(2); Cl(1)—Ru—C(1),103.15(6); Cl(2)—Ru—C(1), 102.79(6); Cl(1)—Ru—C(2), 96.14(5);Cl(2)—Ru—C(2), 92.90(5). Selected torsion angle (°): C(2)—Ru—C(1)—P,−175.06(11).

EXAMPLE 8 Comparison of Relative Catalytic Activities in Ring-ClosingMetathesis

Catalytic runs for the ring-closing metathesis of diethyldiallylmalonatewere performed under standard conditions for each catalyst tested, using1% mol catalyst loadings. The catalysts tested were complex 1c, complex3b, complex 3c, (H₂IMes)Cl₂(3-Br-py)Ru═CHPh, and Schrock's molybdenumalkylidene, having the structure

A stock solution of catalyst was prepared in the drybox by weighing0.0025 mmol in a 1.0 ml graduated flask and dissolving in CD₂Cl₂. Fromthis solution, 400 mL (0.001 mmol) were then transferred into an NMRtube, which was capped with a rubber septum and wrapped with parafilm. Aseparate CD₂Cl₂ diene stock solution was prepared by weighing 1.00 mmolinto a 1 ml volumetric flask and refilling with CD₂Cl₂ to the markedlevel. 100 mL of this diene solution was taken up in a gastight syringe,and taken outside the drybox along with the NMR tube containing thedissolved catalyst. The tube was then immersed into a dry/ice acetonebath (−78° C.) and the diene solution was slowly injected through therubber septum. The sample was shaken and introduced into the NMR probewhich was precooled at 0° C. After allowing the sample to equilibrate,the progress of the reaction at 0° C. was monitored automatically at 3to 10 minutes intervals depending on the catalyst, by measuring thedisappearance of the methylene resonance of diethyldiallylmalonateversus product. FIG. 4 shows the relative rates of conversion for theRCM of diethyldiallylmalonate. The symbols used in the graph are asfollows: ▪—complex 1c; ▴—complex 3b; ●—complex 3c;

—(H₂IMes)Cl₂(3-Br-py)Ru═CHPh; and ♦—Schrock's molybdenum alkylidene.

As may be deduced from FIG. 4, the electron-withdrawing nature of thephosphonium substituent in the carbene ligands of complexes 3b and 3cdoes not impede their ability to conduct olefin metathesis; they areexceptionally active RCM catalysts relative to catalyst precursor 1c.That is, catalyst precursor 1c is a poor initiator and only reachedapproximately 25% conversion after 4 hours. Complex 3b fared somewhatbetter, providing approximately 90% conversion after 4 hours, whileSchrock's catalyst mediated the reaction to a similar point of progressover this time frame. The sigmoidal shape of the curve for 3b isreflective of the different activities of initiating versus propagatingspecies at 0° C. for this catalyst; see Dias (1997), supra. Thetransformation was very rapid for complex 3c, however, which brought thereaction to >90% conversion after only 2 hours at 0° C., twice as fastas the Schrock catalyst under these conditions and, significantly,out-performing the rapidly initiating Grubbs catalyst incorporating therelatively labile 3-bromopyridine ligands. Furthermore, the rate of RCMfor complex 3c is qualitatively similar to the best Blechert catalyst(Wakamatsu et al. (2002) Angew. Chem. 114:2509), a less convenientlyavailable metathesis catalyst.

EXAMPLE 9 Synthesis of [(H₂IMes)Cl₂Ru═CMe(PCy₃)]⁺[BF₄]⁻

(H₂IMes)(Cy₃P)Cl₂Ru≡C: (2c, 80 mg, 0.10 mmol) and [Me₃O]⁺[BF₄]⁻ (15 mg,0.10 mmol) are placed into a 25 ml round bottom flask, which is fittedwith a glass connector with a Kontes valve and attached to the vacuumline. The flask is evacuated and CH₂Cl₂ (10 ml) is vacuum transferredonto the solids at −78° C. The system is warmed to room temperature andstirred for 1 hour. After removing the solvent under vacuum, pentane (20ml) is vacuum transferred onto the residue and the mixture is sonicated,leaving a suspension. After decanting the solvent via cannula, thepowder is dried under vacuum.

EXAMPLE 10 Synthesis of [(H₂IMes)Cl₂Ru═CHCH₂(PPh₃)]⁺[BF₄]⁻

(H₂IMes)(PCy₃)Cl₂Ru═CHPh (1c, 85 mg, 0.10 mmol) and[H₂C═CHCH₂PPh₃]⁺[BF₄]⁻ (39 mg, 0.10 mmol) are placed into a 25 ml roundbottom flask, which is fitted with a glass connector with a Kontes valveand attached to the vacuum line. The flask is evacuated and CH₂Cl₂ (10ml) is vacuum transferred onto the solids at −78° C. The system iswarmed to room temperature and stirred for 1 hour. After removing thesolvent under vacuum, pentane (20 ml) is vacuum transferred onto theresidue and the mixture is sonicated, leaving a suspension. The solventis decanted and the solid washed with additional pentane until thewashings are colorless. The resulting solid is dried under vacuum.

EXAMPLE 11 Synthesis of [(H₂IMes)(py)Cl₂Ru═CHCH₂(PPh₃)]⁺[BF₄]⁻

(H₂IMes)(py)₂Cl₂Ru═CHPh (73 mg, 0.10 mmol) and [H₂C═CHCH₂PPh₃]⁺[BF₄]⁻(39 mg, 0.10 mmol) are placed into a 25 ml round bottom flask, which isfitted with a glass connector with a Kontes valve and attached to thevacuum line. The flask is evacuated and CH₂Cl₂ (10 ml) is vacuumtransferred onto the solids at −78° C. The system is warmed to roomtemperature and stirred for 4 hours. After removing the solvent undervacuum, pentane (20 ml) is vacuum transferred onto the residue and themixture is sonicated, leaving a suspension. After decanting the solventvia cannula, the powder is dried under vacuum.

EXAMPLE 12 Synthesis of [(H₂IMes)(py)Cl₂Ru═CH(PCy₃)]⁺[BF₄]⁻

[(H₂IMes)Cl₂Ru═CH(PCy₃)][BF₄]⁻ (3c, 86 mg, 0.10 mmol) is placed into a25 ml round bottom flask, which is fitted with a glass connector with aKontes valve and attached to the vacuum line. The flask is evacuated andCH₂Cl₂ (10 ml) is vacuum transferred onto the solids at −78° C. Excesspyridine (100 μl, 1.2 mmol) is added by syringe and the system is warmedto room temperature and stirred for 4 hours. After removing the solventunder vacuum, pentane (20 ml) is vacuum transferred onto the residue andthe mixture is sonicated, leaving a suspension. After decanting thesolvent via cannula, the powder is carefully dried under vacuum.

EXAMPLE 13 Alternative Synthesis and Purification of(IH₂Mes)(PC₃)Cl2Ru≡C: (2c)

In a glove box, [(IH₂Mes)(PCy₃)Cl₂Ru═CHPh] (1.00 g, 1.18 mmol) wasdissolved in CH₂Cl₂ (10 ml) and a solution of Feist's ester (200 mg,1.18 mmol) in CH₂Cl₂ (5 ml) was added at room temperature. The reactionmixture was stirred at room temperature for 15 hours. Removal ofvolatiles under reduced pressure gave a waxy brown solid to whichpentane (15 ml) was added and the mixture sonicated for 10 minutes. Thepentane was removed via syringe and the pentane/sonication processrepeated twice. The product was then dissolved in CH₂Cl₂ (5 ml) loadedonto a silica-plug (4×4 cm) and the plug flushed with a 1:1 mixture ofhexane: ethyl acetate and the yellow fraction collected. The volatileswere removed under vacuum. The resulting sandy solid contains ethylacetate of crystallization, however, repeating a process three times ofdissolving the solid in CH₂Cl₂ (5 ml) and removing volatiles underreduced pressure removes all ethyl acetate. The resulting waxy brownsolid was triturated with pentane (10 ml) to afford pure[(IH₂Mes)(PCy₃)Cl₂RuC:] as a sandy solid (725 mg, 80%). This method ofpurification yields a product free of an unidentified small impurity,which causes complications in the isolation of pure[(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[BF₄]⁻. Spectral features matched thosepreviously reported; see Carlson (2002), cited supra.

EXAMPLE 14 Alternative Synthesis of [(IH₂MeS)Cl₂Ru═CH(PCy₃)]⁺[BF₄]⁻

(IH₂MeS)(PCy₃)Cl₂Ru≡C: (100 mg, 0.130 mmol) was dissolved in CH₂Cl₂ (10ml) and cooled at −78° C. A solution of HBF₄ (0.174 M in Et₂O 0.75 ml,0.130 mmol) was added dropwise. The reaction mixture was allowed to warmat room temperature and stirred for 2 hrs. Removal of volatiles underreduced pressure gave a dark waxy brown solid to which pentane (10 ml)was added and the mixture sonicated for 10 minutes. The pentane wasremoved via syringe to afford a brown solid. The solid thus obtainedcontains a small quantity (<5%) of unreacted starting material.Recrystallization from dichloromethane/pentane at −30° C. afforded pure(as judged by ¹H NMR spectroscopy) [(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[BF₄]⁻ (89mg, 80%).

EXAMPLE 15 Synthesis of [(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[OTf]⁻

[(IH₂Mes)(PCy₃)Cl₂Ru≡C:] (200 mg, 0.259 mmol) was weighed into a 50 mlround bottom flask and dissolved in 5 ml of CH₂Cl₂. To this solution38.9 mg (0.259 mmol) of triflic acid, also dissolved in 5 ml of CH₂Cl₂,was added at once. An immediate change in color from yellow to darkbrown was observed. The solution was stirred for 30 minutes and thesolvent was removed under vacuum, leaving a tan solid. The solid wassuspended in pentane (15 ml), stirred for 10 minutes, the solventdecanted via cannula and the product was then dried under vacuum. Theyield was quantitative. Spectral features are identical to thosereported for [(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[B(C₆F₅)₄]⁻, except for thosecorresponding to the new counteranion: ¹⁹F NMR (CD₂Cl₂, 25° C.): δ-79.0(s, CF₃SO₃ ⁻).

EXAMPLE 16 Synthesis of [(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[BPh_(4]) ⁻

[(IH₂Mes)(PCy₃)Cl₂Ru≡C:] (500 mg, 0.648 mol) was dissolved in 15 ml ofCH₂Cl₂ in a 50 ml round bottom flask, and then 97.2 mg (0.648 mmol) oftriflic acid also dissolved in CH₂Cl₂ (5 ml) was added at once. Thereaction mixture was stirred at room temperature for 45 minutes andthen, solid NaBPh₄ was added at once to the brown solution. Thesuspension was stirred for 1 hr at room temperature and was then cooledat −35° C. in the freezer overnight, to induce total precipitation ofthe NaOTf by product. The mixture was then filtered through Celite andthe solvent evaporated, leaving a tan powder. ¹H and ³¹P{¹H} NMR spectraof several batches showed this crude mixture to be pure and no furthermanipulations were necessary. Spectral features are identical to thosereported for [(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺ [B(C₆F₅)₄]⁻, except for thosecorresponding to the new couteranion: ¹H NMR (400 MHz, CD₂Cl₂, 25° C.):δ7.30 (broad, o-C₆H₅B), 6.99 (t, m-C₆H₅B), 6.86 (t,p-C₆H₅B). ¹¹B NMR(CD₂Cl₂, 25° C.): δ-7.23 (s, C₆H₅B).

EXAMPLE 17 Confirmation of Structures by X-Ray Diffraction

The structures of the compounds prepared in Examples 15 and 16 in thesolid state were determined by x-ray diffraction methods and are shownin FIGS. 5 and 6, respectively, with selected bond lengths and angles.In both cases, no close contact between the counteranion and theruthenium center were observed; all distances were greater than 6.99 Åfor [(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[OTf]⁻ (FIG. 5) and greater than 7.83 Å for[(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[BPh₄]⁻ (FIG. 6). Distances and angles in thecationic ruthenium portion are identical (within experimental error) tothose reported for [(IH₂Mes)Cl₂Ru═CH(PCy₃)]⁺[B(C₆F₅)₄]⁻ (see Example 7and FIG. 3).

1. An organometallic complex having the structure of formula (I)

wherein: M is a Group 8 transition metal; L¹ and L² are neutral electron donor ligands; X¹ and X² are anionic ligands; R¹ is hydrogen, C₁-C₁₂ hydrocarbyl, or substituted C₁-C₁₂ hydrocarbyl; W is an optionally substituted and/or optionally heteroatom-containing C₁-C₂₀ hydrocarbylene linkage; Y is a positively charged Group 15 or Group 16 element substituted with hydrogen, C₁-C₁₂ hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl, heteroatom-containing C₁-C₁₂ hydrocarbyl, or substituted heteroatom-containing C₁-C₁₂ hydrocarbyl; Z⁻ is a negatively charged counterion; m is zero or 1; and n is zero or 1; wherein any two or more of L¹, L², X¹, X², R¹, W, and Y can be taken together to form a cyclic group.
 2. The complex of claim 1, wherein M is Ru or Os.
 3. The complex of claim 2, wherein M is Ru.
 4. The complex of claim 3, wherein R¹ is hydrogen or C₁-C₁₂ alkyl.
 5. The complex of claim 4, wherein R¹ is hydrogen.
 6. The complex of claim 1, wherein m and n are zero, such that the complex has the structure of formula (II)


7. The complex of claim 6, wherein Y is selected from P(R²)₃, N(R²)₃, As(R²)₃, S(R²)₂, O(R²)₂, where the R² are independently selected from C₁-C₁₂ hydrocarbyl.
 8. The complex of claim 7, wherein Y is P(R²)₃.
 9. The complex of claim 8, wherein the R² are independently selected from C₁-C₁₂ alkyl and aryl.
 10. The complex of claim 9, wherein the R² are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, cyclopentyl, cyclohexyl, and phenyl.
 11. The complex of claim 6, wherein Y is selected from optionally substituted pyridinyl, pyrazinyl, and imidazolyl.
 12. The complex of claim 6, wherein L¹ is selected from phosphine, sulfonated phosphine, phosphite, phosphinite, phosphonite, arsine, stilbine, ether, amine, amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, substituted pyridine, imidazole, substituted imidazole, pyrazine, thioether, and heteroatom-substituted carbene.
 13. The complex of claim 12, wherein L¹ is a phosphine of the formula PR⁵R⁶R⁷, where R⁵, R⁶, and R⁷ are each independently aryl or C₁-C₁₂ alkyl.
 14. The complex of claim 13, wherein L¹ is selected from tricyclohexylphosphine, tricyclopentylphosphine, triisopropylphosphine, triphenylphosphine, diphenylmethylphosphine, and phenyldimethylphosphine.
 15. The complex of claim 6, wherein L¹ has the structure of formula (III)

wherein: Z¹ and Z² are heteroatoms selected from N, O, S, and P; j is zero when Z¹ is O or S, and j is 1 when Z¹ is N or P; k is zero when Z² is O or S, and k is 1 when Y¹ is N or P; Q¹, Q², Q³, and Q⁴ are independently selected from C₁-C₁₂ hydrocarbylene, substituted C₁-C₁₂ hydrocarbylene, heteroatom-containing C₁-C₁₂ hydrocarbylene, substituted heteroatom-containing C₁-C₁₂ hydrocarbylene, and —(CO)—; w, x, y, and z are independently zero or 1; and R³, R^(3A), R⁴, and R^(4A) are independently selected from hydrogen, C₁-C₂₀ hydrocarbyl, substituted C₁-C₂₀ hydrocarbyl, heteroatom-containing C₁-C₂₀ hydrocarbyl, and substituted heteroatom-containing C₁-C₂₀ hydrocarbyl, such that the complex is a ruthenium carbene complex having the structure of formula (IV)


16. The complex of claim 15, wherein w, x, y, and z are zero, Z¹ and Z¹ are N, and R^(3A) and R^(4A) are linked to form —Q—, such that the complex has the structure of formula (V)

wherein Q is a C₁-C₁₂ hydrocarbylene, substituted C₁-C₁₂ hydrocarbylene, heteroatom-containing C₁-C₁₂ hydrocarbylene, or substituted heteroatom-containing C₁-C₁₂ hydrocarbylene linker, and further wherein two or more substituents on adjacent atoms within Q may be linked to form an additional cyclic group.
 17. The complex of claim 16, wherein Q has the structure —CR⁸R⁹—CR¹⁰R¹¹— or —CR⁸═CR¹⁰—, wherein R⁸, R⁹, R¹⁰, and R¹¹ are independently selected from hydrogen, C₁-C₁₂ hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl, heteroatom-containing C₁-C₁₂ hydrocarbyl, substituted heteroatom-containing C₁-C₁₂ hydrocarbyl, and functional groups, and wherein any two of R⁸, R⁹, R¹⁰, and R¹¹ may be linked together to form a substituted or unsubstituted, saturated or unsaturated ring.
 18. The complex of claim 17, wherein Q has the structure —CR⁸R⁹—CR¹⁰R¹¹—, and R⁸, R⁹, R¹⁰, and R¹¹ are hydrogen.
 19. The complex of claim 17, wherein Q has the structure —CR⁸═CR¹⁰—, and R⁸ and R¹⁰ are hydrogen.
 20. The complex of claim 17, wherein R³ and R⁴ are aromatic, substituted aromatic, heteroaromatic, substituted heteroaromatic, alicyclic, substituted alicyclic, heteroatom-containing alicyclic, or substituted heteroatom-containing alicyclic, composed of from one to about five rings.
 21. The complex of claim 20, wherein R³ and R⁴ are the same and are either aromatic or C₇-C₁₂ alicyclic, if aromatic, each having the structure of formula (VI)

in which R¹², R¹³, and R¹⁴ are each independently hydrogen, C₁-C₁₂ alkyl, C₁-C₁₂ alkoxy, C₅-C₁₄ aryl, substituted C₅-C₁₄ aryl, or halide.
 22. The complex of claim 21, wherein R³ and R⁴ are mesityl.
 23. The complex of claim 6, wherein X¹and X² are independently selected from hydrogen, halide, C₁-C₂₀ alkyl, C₅-C₂₀ aryl, C₁-C₂₀ alkoxy, C₅-C₂₀ aryloxy, C₂-C₂₀ alkoxycarbonyl, C₆-C₂₀ aryloxycarbonyl, C₂-C₂₀ acyl, C₂-C₂₀ acyloxy, C₁-C₂₀ alkylsulfonato, C₅-C₂₀ arylsulfonato, C₁-C₂₀ alkylsulfanyl, C₅-C₂₀ arylsulfanyl, C₁-C₂₀ alkylsulfinyl, or C₅-C₂₀ arylsulfinyl, any of which, with the exception of hydrogen and halide, are optionally further substituted with one or more groups selected from halide, C₁-C₆ alkyl, C₁-C₆ alkoxy, and phenyl.
 24. The complex of claim 23, wherein X¹ and X² are selected from halide, mesylate, tosylate, fluorinated C₂-C₂₀ acyloxy, fluorinated C₁-C₂₀ alkylsulfonate, fluorinated C₁-C₂₀ alkoxy, and fluorinated C₅-C₂₀ aryloxy.
 25. The complex of claim 24, wherein X¹ and X² are chloro.
 26. The complex of claim 6, wherein [Z]⁻ is selected from [B(C₆F₅)₄]⁻, [BF₄]⁻, [B(C₆H₆)₄]⁻, [CF₃S(O)₃]⁻, [PF₆]⁻, [SbF₆]⁻, and [AlCl₄]⁻ [FSO₃]⁻, [CB₁₁H₆Cl₆]⁻, [CB₁₁H₆Br₆]⁻, and [SO₃F:SbF₅]⁻.
 27. The complex of claim 26, wherein Z⁻ is of the formula B(R¹⁵)₄ ⁻ where R¹⁵ is fluoro, aryl, or perfluorinated aryl.
 28. The complex of claim 27, wherein R¹⁵ is fluoro or perfluorinated aryl.
 29. The complex of claim 6, wherein: L¹ is 1,3-dimesitylimidazole-2-ylidene (IMes) or 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene (H₂IMes); X¹ and X² are chloro; Y is P(R²)₃, wherein the R² are independently selected from C₁-C₆ alkyl and phenyl; and Z⁻ is BF₄ ⁻ or B(C₆F₅)⁻.
 30. The complex of claim 1, wherein m is 1 and n is 1, such that the complex has the structure of formula (VII)


31. The complex of claim 30, wherein W is an optionally substituted C₁-C₁₂ alkylene linkage.
 32. The complex of claim 31, wherein L¹ is selected from phosphine, sulfonated phosphine, phosphite, phosphinite, phosphonite, arsine, stilbine, ether, amine, amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, substituted pyridine, imidazole, substituted imidazole, pyrazine, thioether, and heteroatom-substituted carbene, and L² is selected from phosphine, sulfonated phosphine, phosphite, phosphinite, phosphonite, arsine, stilbine, ether, amine, amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, substituted pyridine, imidazole, substituted imidazole, pyrazine, and thioether.
 33. The complex of claim 32, wherein L¹ is N-heterocyclic carbene ligand.
 34. The complex of claim 33, wherein L² is a phosphine ligand.
 35. The complex of claim 34, wherein L² is of the formula PR⁵R⁶R⁷, where R⁵, R⁶, and R⁷ are each independently aryl or C₁-C₁₂ alkyl.
 36. The complex of claim 35, wherein: L¹ is 1,3-dimesitylimidazole-2-ylidene (IMes) or 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene (H₂IMes); L² is selected from tricyclohexylphosphine, tricyclopentylphosphine, triisopropylphosphine, triphenylphosphine, diphenylmethylphosphine, and phenyldimethylphosphine; W is an optionally substituted C₁-C₁₂ alkylene linkage; X¹ and X² are chloro; Y is P(R²)₃, wherein the R² are independently selected from C₁-C₆ alkyl and phenyl; and Z⁻ is BF₄ ⁻ or B(C₆F₅)⁻.
 37. A method for synthesizing an organometallic complex having the structure of formula (XI)

wherein M is a Group 8 transition metal, L¹ is a neutral electron donor ligand, X¹ and X² are anionic ligands, R¹ is hydrogen, C₁-C₁₂ hydrocarbyl, or substituted C₁-C₁₂ hydrocarbyl, Y is a positively charged Group 15 or Group 16 element substituted with hydrogen, C₁-C₁₂ hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl, heteroatom-containing C₁-C₁₂ hydrocarbyl, or substituted heteroatom-containing hydrocarbyl, and Z⁻ is a negatively charged ion, the method comprising: contacting a Group 8 transition metal carbide having the structure (X¹X²)(L¹Y)M≡C: with an ionic reagent of the formula [R¹]⁺[Z]⁻.
 38. The method of claim 37, wherein M is Ru or Os.
 39. The method of claim 38, wherein M is Ru.
 40. The method of claim 39, wherein the [R¹]⁺ moiety in the ionic reagent is associated with a polar solvent.
 41. The method of claim 40, wherein R¹ is hydrogen.
 42. The method of claim 41, wherein [Z]⁻ is selected from [B(C₆F₅)₄]⁻, [BF₄]⁻, [B(C₆H₆)₄]⁻, [CF₃S(O)₃]⁻, [PF₆]⁻, [SbF₆]⁻, and [AlCl₄]⁻ [FSO₃]⁻, [CB₁₁H₆Cl₆]⁻, [CB₁₁H₆Br₆]⁻, and [SO₃F:SbF₅]⁻.
 43. A method for synthesizing an organometallic complex having the structure of formula (II)

wherein L¹ is a neutral electron donor ligand, X¹ and X² are anionic ligands, R¹ is hydrogen, Y is a C₁-C₁₂ hydrocarbyl-substituted, positively charged Group 15 or Group 16 element, and Z⁻ is of the formula B(R¹⁵)₄ ⁻ where R¹⁵ is fluoro, aryl, or perfluorinated aryl, the method comprising: (a) contacting (i) a ruthenium complex having the structure (X¹X²)(L¹Y)Ru═CHR¹⁶ where R¹⁶ is C₁-C₂₀ hydrocarbyl with (ii) a reagent effective to convert the ruthenium complex to the ruthenium carbide (X¹X²)(Y)Ru≡C:; and (b) contacting the ruthenium carbide with a protonating reagent of the formula [H(OR₂)₂]⁺[B(R¹⁵)₄]⁻ where R is C₁-C₆ hydrocarbyl.
 44. A method for synthesizing an organometallic complex having the structure of formula (XII)

wherein M is a Group 8 transition metal, L¹ and L² are neutral electron donor ligands, X¹ and X² are anionic ligands, R¹ is hydrogen, C₁-C₁₂ hydrocarbyl, or substituted C₁-C₁₂ hydrocarbyl, W is an optionally substituted and/or optionally heteroatom-containing C₁-C₂₀ hydrocarbylene linkage, Y is a positively charged Group 15 or Group 16 element substituted with hydrogen, C₁-C₁₂ hydrocarbyl, substituted C₁-C₁₂ hydrocarbyl, heteroatom-containing C₁-C₁₂ hydrocarbyl, or substituted heteroatom-containing hydrocarbyl, and Z⁻ is a negatively charged ion, the method comprising: contacting an organometallic complex having the structure (X¹X²)(L¹L²)M═CHR¹⁶ where R¹⁶ is C₁-C₂₀ hydrocarbyl with an ionic reagent having the structure H₂C═CR¹—W—Y⁺Z⁻ under conditions effective to enable cross metathesis between the transition metal alkylidene group in the complex and the olefinic moiety in the reagent.
 45. A method for synthesizing an organometallic complex having the structure of formula (VII)

wherein L¹ and L² are neutral electron donor ligands, X¹ and X² are anionic ligands, R¹ is hydrogen, C₁-C₁₂ hydrocarbyl, or substituted C₁-C₁₂ hydrocarbyl, W is an optionally substituted C₁-C₁₂ alkylene linkage, Y is a C₁-C₁₂ hydrocarbyl-substituted, positively charged Group 15 or Group 16 element, and Z⁻ is of the formula B(R¹⁵)₄ ⁻ where R¹⁵ is fluoro, aryl, or perfluorinated aryl, the method comprising: contacting a ruthenium complex having the structure (X¹X²)(L¹L²)Ru═CHR¹⁶ where R¹⁶ is C₁-C₂₀ hydrocarbyl with an ionic reagent having the structure H₂C═CR¹—W—Y⁺Z⁻ under conditions effective to enable cross metathesis between the ruthenium alkylidene group in the complex and the olefinic moiety in the reagent.
 46. A method for catalyzing an olefin metathesis reaction, comprising contacting an olefinic reactant with a catalytically effective amount of the complex of any one of claims 1, 6, 29, 30, and 36 under reaction conditions effective to enable olefin metathesis.
 47. The method of claim 46, wherein the olefinic reactant is cyclic and the metathesis reaction is ring-opening metathesis polymerization (ROMP).
 48. The method of claim 46, wherein the olefinic reactant is an acyclic diene, and the metathesis reaction is ring-closing metathesis (RCM) or acyclic diene metathesis (ADMET).
 49. The method of claim 46, wherein two olefinic reactants are contacted with a catalytically effective amount of the complex, and the metathesis reaction is cross-metathesis. 